Bump pip from 9.0.1 to 21.1

Bumps [pip](https://github.com/pypa/pip) from 9.0.1 to 21.1.
- [Release notes](https://github.com/pypa/pip/releases)
- [Changelog](https://github.com/pypa/pip/blob/main/NEWS.rst)
- [Commits](pypa/pip@9.0.1...21.1)

---
updated-dependencies:
- dependency-name: pip
  dependency-type: direct:production
...

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

Author: dependabot[bot]

setup.py

@@ -11,7 +11,7 @@
 
 requirements = [
     'wheel==0.38.1',
-    'pip==9.0.1',
+    'pip==21.1',
 ]
 
 test_requirements = [