Add download stats badge.

[sodul]

This adds a downloads stats badge to the main readme which helps show the popularity of green.

Moved the text around a bit to be consistent with other popular python packages and added the badges to the readme that is published on pypi.org.

[sodul]

[coveralls]

coverage: 95.232%. remained the same
when pulling 3b75ea1 on clumio-oss:main
into 8cabab8 on CleanCut:main.

[sodul]

There is a known bug with GH actions being broken on macos-latest and python 3.8 and 3.9.

actions/setup-python#850

[sodul]

Python 3.8 and 3.9 are now fixed for macos-latest but we are now getting this error on 3.8:

lxml/etree.cpython-38-darwin.so, 0x0002): symbol not found in flat namespace '_exsltDateXpathCtxtRegister'

This is completely unrelated to our changes if this is a persistent problem I can look into the issue further. My guess is that for this target the etree.cpython-38-darwin.so needs to be recompiled from sources in order to run properly. Alternatively we could target macOS 13 instead of latest for 3.8. Since it will be EOL later this year that might be the simplest thing to do.