Update fixate-requirements.py to cope with PIP 20.3.3

[amanda11]

Building upon #5060. Updates to fixate-requirements.py to see if can use newer version of pip for make requirements.

[amanda11]

Need to resolve problem seen when try and building this version of ST2 using the dockerfiles from StackStorm/st2packaging-dockerfiles#97:

ERROR: Command errored out with exit status 1:
[wheelhouse: st2]           command: /usr/bin/python3 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-wheel-njg1eihv/simplejson_b53c2b0962984f95ae8a5c6c5ab9b98d/setup.py'"'"'; __file__='"'"'/tmp/pip-wheel-njg1eihv/simplejson_b53c2b0962984f95ae8a5c6c5ab9b98d/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-pip-egg-info-w_idsqh0
[wheelhouse: st2]               cwd: /tmp/pip-wheel-njg1eihv/simplejson_b53c2b0962984f95ae8a5c6c5ab9b98d/
[wheelhouse: st2]          Complete output (6 lines):
[wheelhouse: st2]          Traceback (most recent call last):
[wheelhouse: st2]            File "<string>", line 1, in <module>
[wheelhouse: st2]            File "/tmp/pip-wheel-njg1eihv/simplejson_b53c2b0962984f95ae8a5c6c5ab9b98d/setup.py", line 39
[wheelhouse: st2]              except DistutilsPlatformError, x:
[wheelhouse: st2]                                           ^
[wheelhouse: st2]          SyntaxError: invalid syntax

[amanda11]

Looks like if you upgrade the version of pip used when you do the build that it has a different way of determining dependencies, and it goes back through lots of old versions - if it gets to versions that aren't python3 compatible then it fails. So have to then fixate those requirements so the min is at least a py3 version.
See: pypa/pip#8713

[amanda11]

The build takes much longer with this pip, will need to probably update the version requirements to much higher ones to enable it to have less versions to compare when it works out its dependencies.

[cognifloyd]

We just reformatted the code with black. (Hooray!) And this PR got caught in the cross fire. (Arrgh!)
This is just a note to let you know why merging master into this branch will be a bit less fun this time around and to commiserate on how hard it is to get pip updated...

[cognifloyd]

Just a few comment suggestions. The code looks great.

[cognifloyd]

CI failures are resolved on master. Merging should resolve them.

[cognifloyd]

Weird. I wonder why GHA didn't check the last commit.

[amanda11]

Related change is merged, but waiting for dockerfiles to be published: StackStorm/st2packaging-dockerfiles#98
May need to wait for StackStorm/st2-packages#684 to be merged

[arm4b]

👍

Thanks a lot for diving deep here!