diff --git a/poetry.lock b/poetry.lock
index f4b6868..56c32a8 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -693,17 +693,17 @@ python-versions = "*"
 
 [[package]]
 name = "sphinx"
-version = "3.3.1"
+version = "4.1.1"
 description = "Python documentation generator"
 category = "main"
 optional = true
-python-versions = ">=3.5"
+python-versions = ">=3.6"
 
 [package.dependencies]
 alabaster = ">=0.7,<0.8"
 babel = ">=1.3"
 colorama = {version = ">=0.3.5", markers = "sys_platform == \"win32\""}
-docutils = ">=0.12"
+docutils = ">=0.14,<0.18"
 imagesize = "*"
 Jinja2 = ">=2.3"
 packaging = "*"
@@ -712,15 +712,15 @@ requests = ">=2.5.0"
 snowballstemmer = ">=1.1"
 sphinxcontrib-applehelp = "*"
 sphinxcontrib-devhelp = "*"
-sphinxcontrib-htmlhelp = "*"
+sphinxcontrib-htmlhelp = ">=2.0.0"
 sphinxcontrib-jsmath = "*"
 sphinxcontrib-qthelp = "*"
-sphinxcontrib-serializinghtml = "*"
+sphinxcontrib-serializinghtml = ">=1.1.5"
 
 [package.extras]
 docs = ["sphinxcontrib-websupport"]
-lint = ["flake8 (>=3.5.0)", "flake8-import-order", "mypy (>=0.790)", "docutils-stubs"]
-test = ["pytest", "pytest-cov", "html5lib", "typed-ast", "cython"]
+lint = ["flake8 (>=3.5.0)", "isort", "mypy (>=0.900)", "docutils-stubs", "types-typed-ast", "types-pkg-resources", "types-requests"]
+test = ["pytest", "pytest-cov", "html5lib", "cython", "typed-ast"]
 
 [[package]]
 name = "sphinx-jsonschema"
@@ -776,11 +776,11 @@ test = ["pytest"]
 
 [[package]]
 name = "sphinxcontrib-htmlhelp"
-version = "1.0.3"
+version = "2.0.0"
 description = "sphinxcontrib-htmlhelp is a sphinx extension which renders HTML help files"
 category = "main"
 optional = true
-python-versions = ">=3.5"
+python-versions = ">=3.6"
 
 [package.extras]
 lint = ["flake8", "mypy", "docutils-stubs"]
@@ -811,7 +811,7 @@ test = ["pytest"]
 
 [[package]]
 name = "sphinxcontrib-serializinghtml"
-version = "1.1.4"
+version = "1.1.5"
 description = "sphinxcontrib-serializinghtml is a sphinx extension which outputs \"serialized\" HTML files (json and pickle)."
 category = "main"
 optional = true
@@ -907,7 +907,7 @@ docs = ["sphinx", "sphinx_rtd_theme", "sphinx-jsonschema"]
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.6"
-content-hash = "512480e29a4be88ea52c2e08b1d67dba3ae2f1f5553fc3a12d4d65efb364335a"
+content-hash = "da257b46741a59b793df075555b48391400c99e2b2f1c60f45127e7a65630ea4"
 
 [metadata.files]
 alabaster = [
@@ -1382,8 +1382,8 @@ snowballstemmer = [
     {file = "snowballstemmer-2.0.0.tar.gz", hash = "sha256:df3bac3df4c2c01363f3dd2cfa78cce2840a79b9f1c2d2de9ce8d31683992f52"},
 ]
 sphinx = [
-    {file = "Sphinx-3.3.1-py3-none-any.whl", hash = "sha256:d4e59ad4ea55efbb3c05cde3bfc83bfc14f0c95aa95c3d75346fcce186a47960"},
-    {file = "Sphinx-3.3.1.tar.gz", hash = "sha256:1e8d592225447104d1172be415bc2972bd1357e3e12fdc76edf2261105db4300"},
+    {file = "Sphinx-4.1.1-py3-none-any.whl", hash = "sha256:3d513088236eef51e5b0adb78b0492eb22cc3b8ccdb0b36dd021173b365d4454"},
+    {file = "Sphinx-4.1.1.tar.gz", hash = "sha256:23c846a1841af998cb736218539bb86d16f5eb95f5760b1966abcd2d584e62b8"},
 ]
 sphinx-jsonschema = [
     {file = "sphinx-jsonschema-1.16.8.tar.gz", hash = "sha256:5728b3ece1fe475c285d5ae16953242c51b4e6852f48f0bb734cd8408f3ac8b3"},
@@ -1401,8 +1401,8 @@ sphinxcontrib-devhelp = [
     {file = "sphinxcontrib_devhelp-1.0.2-py2.py3-none-any.whl", hash = "sha256:8165223f9a335cc1af7ffe1ed31d2871f325254c0423bc0c4c7cd1c1e4734a2e"},
 ]
 sphinxcontrib-htmlhelp = [
-    {file = "sphinxcontrib-htmlhelp-1.0.3.tar.gz", hash = "sha256:e8f5bb7e31b2dbb25b9cc435c8ab7a79787ebf7f906155729338f3156d93659b"},
-    {file = "sphinxcontrib_htmlhelp-1.0.3-py2.py3-none-any.whl", hash = "sha256:3c0bc24a2c41e340ac37c85ced6dafc879ab485c095b1d65d2461ac2f7cca86f"},
+    {file = "sphinxcontrib-htmlhelp-2.0.0.tar.gz", hash = "sha256:f5f8bb2d0d629f398bf47d0d69c07bc13b65f75a81ad9e2f71a63d4b7a2f6db2"},
+    {file = "sphinxcontrib_htmlhelp-2.0.0-py2.py3-none-any.whl", hash = "sha256:d412243dfb797ae3ec2b59eca0e52dac12e75a241bf0e4eb861e450d06c6ed07"},
 ]
 sphinxcontrib-jsmath = [
     {file = "sphinxcontrib-jsmath-1.0.1.tar.gz", hash = "sha256:a9925e4a4587247ed2191a22df5f6970656cb8ca2bd6284309578f2153e0c4b8"},
@@ -1413,8 +1413,8 @@ sphinxcontrib-qthelp = [
     {file = "sphinxcontrib_qthelp-1.0.3-py2.py3-none-any.whl", hash = "sha256:bd9fc24bcb748a8d51fd4ecaade681350aa63009a347a8c14e637895444dfab6"},
 ]
 sphinxcontrib-serializinghtml = [
-    {file = "sphinxcontrib-serializinghtml-1.1.4.tar.gz", hash = "sha256:eaa0eccc86e982a9b939b2b82d12cc5d013385ba5eadcc7e4fed23f4405f77bc"},
-    {file = "sphinxcontrib_serializinghtml-1.1.4-py2.py3-none-any.whl", hash = "sha256:f242a81d423f59617a8e5cf16f5d4d74e28ee9a66f9e5b637a18082991db5a9a"},
+    {file = "sphinxcontrib-serializinghtml-1.1.5.tar.gz", hash = "sha256:aa5f6de5dfdf809ef505c4895e51ef5c9eac17d0f287933eb49ec495280b6952"},
+    {file = "sphinxcontrib_serializinghtml-1.1.5-py2.py3-none-any.whl", hash = "sha256:352a9a00ae864471d3a7ead8d7d79f5fc0b57e8b3f95e9867eb9eb28999b92fd"},
 ]
 toml = [
     {file = "toml-0.10.2-py2.py3-none-any.whl", hash = "sha256:806143ae5bfb6a3c6e736a764057db0e6a0e05e338b5630894a5f779cabb4f9b"},
diff --git a/pyproject.toml b/pyproject.toml
index 4e835dd..a41bdbd 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -28,7 +28,7 @@ requests-toolbelt = "^0.9.1"
 click = "^7.1.2"
 
 # Docs build dependencies
-sphinx = { version = "^3.3.0", optional = true }
+sphinx = { version = ">=3.3,<5.0", optional = true }
 sphinx_rtd_theme = { version = "^0.5.0", optional = true }
 sphinx-jsonschema = { version = "^1.15", optional = true }