Resolved dependency conflict with importlib-metadata on Python 3.7

Details:

* Increased the minimum version of virtualenv to 20.15.0 for Python
  <= 3.11 in order to resolve the following dependency conflict:

    The user requested importlib-metadata<5 and >=4.8.3
    build 0.5.0 depends on importlib-metadata>=0.22; python_version < "3.8"
    virtualenv 20.1.0 depends on importlib-metadata<3 and >=0.12;
      python_version < "3.8"
    The user requested (constraint) importlib-metadata==4.8.3

Signed-off-by: Andreas Maier <[email protected]>

dev-requirements.txt

@@ -31,7 +31,9 @@ packaging>=21.0; python_version >= '3.6'
 # Virtualenv
 # build requires virtualenv.cli_run which was added in 20.1
 # virtualenv 20.0 requires six<2,>=1.12.0
-virtualenv>=20.1.0
+# virtualenv 20.16.0 removed support for Python<3.6
+virtualenv>=20.15.0; python_version <= '3.11'
+virtualenv>=20.23.0; python_version >= '3.12'
 
 # Coverage reporting (no imports, invoked via coveralls script):
 coverage>=5.0

minimum-constraints.txt

@@ -143,7 +143,8 @@ packaging==20.5; python_version <= '3.5'
 packaging==21.0; python_version >= '3.6'
 
 # Virtualenv
-virtualenv==20.1.0
+virtualenv==20.15.0; python_version <= '3.11'
+virtualenv==20.23.0; python_version >= '3.12'
 
 # Coverage reporting (no imports, invoked via coveralls script):
 coverage==5.0