Peter M. Groen / oletools

(1) Cannot open a temp file for writing from 2 python processes
    simultaneously
(2) Need proper environment setup for Popen (thanks to metatoaster's
    reply on stackoverflow https://stackoverflow.com/a/72845540/4405656)
(3) Need different os-separator, so replace hard-coded '/' with
    os.path.join or os.sep
(4) Minor cleanup of imports & whitespace in test_issue_*.py

There are still 2 tests that should be adapted to Windows, but those are
lower-prio in my eyes.

Also, unittest run on my windows VM creates many resource warnings due to
non-closed file descriptors. Should address that some (future) day.

Want this to check why requirements installation does not happen as expected

Save computing time by failing immediately if any test fails. If we
return early from one VM, the others are stopped, as well, so this
saves lots of parallel time.

Could not find a way to say "newest pypy"; "pypy3" or "pypy3.x" did not
work

Use github actions for Continuous Integration

Exclude RTF files from language statistics

Fix a SyntaxWarning in Python 3.8+

Fix unittests

tests: Re-enable samples skipped because of #215

Some samples triggered antivirus engines, issues #215 and #217 ended with
the agreement to encapsulate problematic samples in encrypted zip
containers and decrypt them on-the-fly. Initial support for this was added
but that did not cover 5 tests. Create on-the-fly decryption for these
tests as well and re-enable them.

Arg "keepends" is a non-keyword-arg in python 2.7

Before using log_helper in olevba logged a "finalization message", which is
no longer required. Had forgotten to update unittests.

Oleobj preserve file extension

Test xlm samples