Project: Don't use poetry.lock, because it's a library

Otherwise, scheduled runs would not use the most recent libraries
relative to their version constraints, so it would defer a fragment
of the continuous testing procedure.

Versions pinned in `poetry.lock` files will net have any meaning for
downstream users installing your package anyway, and, as such, are only
suitable for exact-pinning dependency versions of _applications_.

On the other hand, _libraries_ need to work with a wide range of
dependencies up and down, and are, as such, not suitable for applying
corresponding exact-pinning procedures.

.github/workflows/_lint.yml

@@ -49,12 +49,6 @@ jobs:
         run: |
           poetry check
 
-      - name: Check lock file
-        shell: bash
-        working-directory: ${{ inputs.working-directory }}
-        run: |
-          poetry lock --check
-
       - name: Install dependencies
         # Also installs dev/lint/test/typing dependencies, to ensure we have
         # type hints for as many of our libraries as possible.

.gitignore

@@ -3,3 +3,6 @@ __pycache__
 .idea
 .mypy_cache
 coverage.xml
+# Don't use `poetry.lock`, because it's a library.
+# https://github.com/python-poetry/poetry/issues/2861
+poetry.lock