Use GitHub Actions instead of Travis (CU-86drj1yqw).

[micahdbak]

This PR is in progress.

[trisapeace]

Task linked: CU-86drj1yqw Look at viability of GitHub Actions vs Travis

[micahdbak]

Immediately noticing:

• GitHub Actions is much faster than Travis.
  • This is likely because Actions are performed in parallel, whereas Travis is sequential.
  • This is great for several devs working at the same time!
• GitHub Actions is configured very similarly to Travis.
  • Easy to work with!

Still need to:

• [ ] Configure PostgreSQL 12 for the Run Server Tests Workflow
• [ ] Create Workflow for Firmware Tests (+ Linting and Formatting Checks)

[micahdbak]

Being done by Elana!