py-pip: upgrade to version 21.1.1

[chadcatlett]

Description

pip 21.1 can generate errors when doing pip install --user. It refers users to checkout pip issue 9617. Upgrading to the latest stable pip fixes the issue.

Here is an example of a slightly redacted error message the current version can generate:

WARNING: Value for scheme.platlib does not match. Please report this to <https://github.com/pypa/pip/issues/9617>
distutils: /Users/ccatlett/Library/Python/3.9/lib/python/site-packages
sysconfig: /Users/ccatlett/Library/Python/3.9/lib/python3.9/site-packages
WARNING: Value for scheme.purelib does not match. Please report this to <https://github.com/pypa/pip/issues/9617>
distutils: /Users/ccatlett/Library/Python/3.9/lib/python/site-packages
sysconfig: /Users/ccatlett/Library/Python/3.9/lib/python3.9/site-packages
WARNING: Additional context:
user = True
home = None
root = None
prefix = None

Type(s)

• bugfix
• enhancement
• security fix

Tested on

macOS 10.15.7 19H1030 x86_64
Xcode 12.4 12D4e

Verification

• followed our Commit Message Guidelines?
• squashed and minimized your commits?
• checked that there aren't other open pull requests for the same change?
• checked your Portfile with port lint?
• tried a full install with sudo port -vst install?
• tested basic functionality of all binary files?

[macportsbot]

Notifying maintainers:
@stromnov for port py-pip.