Update pytest requirement from ==6.1.* to >=6.1,<6.3

Updates the requirements on [pytest](https://github.com/pytest-dev/pytest) to permit the latest version.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/main/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@6.1.0...6.2.2)

Signed-off-by: dependabot[bot] <support@github.com>

setup.py

@@ -39,7 +39,7 @@ def read(*parts):
     'codecov==2.1.*',
     'coverage>=5.3,<5.6',
     'pytest-cov==2.10.*',
-    'pytest==6.1.*',
+    'pytest>=6.1,<6.3',
     'pycodestyle==2.6.*'
 ]