Python import maintenance

v0.4-2

Fixes

• Import from collections.abc instead of collections. [Stephen L Arnold]

• Use correct imports for defaultDict, fix CI, bump post version (#3) [Steve Arnold]

Python and CI cleanup

Fix some deps and packaging issues, add CI on Linux, Macos, Windows

Merge PR branches from @Lucas-C and @edumco

• Fixing decodegraphics.py import error
• Update "Other libs" section of README.md
• README.rst: moving pikepdf to correct section
• fix: pkg: install pycrypto-comaptible form of pycryptodome
• fix: remove StopIteration handler in tokens.py and just return
• chg: ci: set PYTHONIOENCODING to utf-8 for all platforms and normalize line endings