Code check fails because there is no valid version of jsmin

[JPBergsma]

When I created PR#937 the test fails with the error message:
ERROR: No matching distribution found for jsmin>=2.2.2

ERROR: Command errored out with exit status 1:
command: /opt/hostedtoolcache/Python/3.8.11/x64/bin/python -c 'import io, os, sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-wj_6aaxj/jsmin_3373d4e1cba348b681a19efd274ceeb4/setup.py'"'"'; file='"'"'/tmp/pip-install-wj_6aaxj/jsmin_3373d4e1cba348b681a19efd274ceeb4/setup.py'"'"';f = getattr(tokenize, '"'"'open'"'"', open)(file) if os.path.exists(file) else io.StringIO('"'"'from setuptools import setup; setup()'"'"');code = f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, file, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-pip-egg-info-bczs0nja
cwd: /tmp/pip-install-wj_6aaxj/jsmin_3373d4e1cba348b681a19efd274ceeb4/
Complete output (1 lines):
error in jsmin setup command: use_2to3 is invalid.

[ml-evs]

I think the first one is a misleading error as jsmin 2.2.2 definitely exists (https://pypi.org/project/jsmin/).

Let's run a dependabot check to see if this has already been fixed upstream, and if not, we can try pinning the version in your PR.

[JPBergsma]

See also this issue tikitu/jsmin#33

[ml-evs]

Let's just follow everyone else in that thread and remove the mkdocs minify plugin, we don't need it and it hasn't been updated in a while.