Bump pip from 20.2 to 20.2.2 in /.github/workflows

Bumps [pip](https://github.com/pypa/pip) from 20.2 to 20.2.2.
- [Release notes](https://github.com/pypa/pip/releases)
- [Changelog](https://github.com/pypa/pip/blob/master/NEWS.rst)
- [Commits](pypa/pip@20.2...20.2.2)

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

Author: dependabot[bot]

.github/workflows/constraints.txt

@@ -1,4 +1,4 @@
-pip==20.2
+pip==20.2.2
 nox==2020.5.24
 poetry==1.0.10
 virtualenv==20.0.31