Remove high constraint for importlib-metadata (#1764)

Since importlib-metadata is a backport from CPython, new major versions
are much more likely to be to adjust supported Python versions, and not
change the API. Remove the upper bound on the version constraint.

Closes #1763.

Author: pkolbus

CONTRIBUTORS

@@ -87,6 +87,7 @@ Oliver Bestwalter
 Pablo Galindo
 Paul Moore
 Paweł Adamczak
+Peter Kolbus
 Philip Thiem
 Pierre-Jean Campigotto
 Pierre-Luc Tessier Gagné

docs/changelog/1763.feature.rst

@@ -0,0 +1,2 @@
+Relax importlib requirement to allow 3.0.0 or any newer version - by
+:user:`pkolbus`

setup.cfg

@@ -47,7 +47,7 @@ install_requires =
     toml>=0.9.4
     virtualenv!=20.0.0,!=20.0.1,!=20.0.2,!=20.0.3,!=20.0.4,!=20.0.5,!=20.0.6,!=20.0.7,>=16.0.0
     colorama>=0.4.1 ;platform_system=="Windows"
-    importlib-metadata>=0.12,<3;python_version<"3.8"
+    importlib-metadata>=0.12;python_version<"3.8"
 python_requires = >=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*
 
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