Sets CI to only run on pushes to main branch

[morganzellers]

Checklist:

• Did you sign the Contributor License Agreement?
• Does the CI pipeline pass?

[Richard-Gist]

So with this, we should only run this in Main, and everyone else will get it running in their main, or when they specifically request a run through workflow_dispatch. With our working methods, we will only run the tests once per commit instead of twice. AND it is now halving the boxes we use on each commit when we have a draft PR open.

We've discussed all this and this is what we want going forward.

[codecov-commenter]

Codecov Report

Merging #122 (6693c44) into main (e5150d4) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #122   +/-   ##
=======================================
  Coverage   94.31%   94.31%           
=======================================
  Files          77       77           
  Lines        1883     1883           
=======================================
  Hits         1776     1776           
  Misses        107      107           

---

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 f4c8821...6693c44. Read the comment docs.