PR: Add fastmat and pythoncom to UMR blacklist.

[dalthviz]

Pull Request Checklist

• Read and followed this repo's Contributing Guidelines
• Based your PR on the latest version of the correct branch (master or 3.x)
• Followed PEP8 for code style
• Ensured your pull request hasn't eliminated unrelated blank lines/spaces,
  modified the spyder/defaults directory, or added new icons/assets
• Wrote at least one-line docstrings for any new functions
• Added at least one unit test covering the changes, if at all possible
• Described your changes and the motivation for them below
• Noted what issue(s) this pull request resolves, creating one if needed
• Included a screenshot, if this PR makes any visible changes to the UI

Description of Changes

Add fastmat (Python 2 only) and pythoncom to UMR blacklist

Issue(s) Resolved

Fixes #7190