Bump pip from 21.0.1 to 21.1

Bumps [pip](https://github.com/pypa/pip) from 21.0.1 to 21.1.
- [Release notes](https://github.com/pypa/pip/releases)
- [Changelog](https://github.com/pypa/pip/blob/main/NEWS.rst)
- [Commits](pypa/pip@21.0.1...21.1)

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

Author: dependabot[bot]

requirements.txt

@@ -2,6 +2,6 @@
 # This makes the build more reproducible
 # When a new version is released the dependabot makes a PR
 
-pip==21.0.1
+pip==21.1
 setuptools==56.0.0
 wheel==0.36.2