Bugfix: Could not send messages to groups ending in "="

[oddlama]

Description:

A lot of signal groups end in "=" as they are base64 encoded. The = isn't matched and therefore stripped before passing it to the api, resulting in the group not being recognized. The fix is extremely simple.

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• No lint errors (use flake8)
• 100% test coverage

[codecov-commenter]

Codecov Report

Base: 100.00% // Head: 100.00% // No change to project coverage 👍

Coverage data is based on head (3d1e506) compared to base (2d33935).
Patch has no changes to coverable lines.

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #670   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          114       114           
  Lines        14684     14684           
  Branches      2783      2783           
=========================================
  Hits         14684     14684           

Impacted Files	Coverage Δ
apprise/plugins/NotifySignalAPI.py	100.00% <ø> (ø)

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[caronc]

Thank you for the PR. It looks good 🚀