Bump minimal tox version (#32)

tox.ini

@@ -4,7 +4,7 @@ envlist = lint, py3, pypy3
 # requires if they are not available on the host system. This requires the
 # locally installed tox to have a minimum version 3.3.0. This means the names
 # of the configuration options are still according to the tox 3.x syntax.
-minversion = 4.2.4
+minversion = 4.4.3
 # This version of virtualenv will install setuptools version 65.5.0 and pip
 # 22.3. These versions fully support python projects defined only through a
 # pyproject.toml file (PEP-517/PEP-518/PEP-621)