Add GitHub Sponsors

[JimBobSquarePants]

Prerequisites

• I have written a descriptive pull-request title
• I have verified that there are no overlapping pull-requests open
• I have verified that I am following matches the existing coding patterns and practice as demonstrated in the repository. These follow strict Stylecop rules 👮.
• I have provided test coverage for my change (where applicable)

Description

Adds Github Sponsors button and updates Open Collective avatars. Also configured actions to ignore trivial non-code changes.

[codecov]

Codecov Report

Merging #1311 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1311   +/-   ##
=======================================
  Coverage   82.76%   82.76%           
=======================================
  Files         689      689           
  Lines       30721    30721           
  Branches     3473     3473           
=======================================
  Hits        25427    25427           
  Misses       4587     4587           
  Partials      707      707           

Flag	Coverage Δ
#unittests	82.76% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 64e7d6a...cd9e68e. Read the comment docs.