* Revamp PDBFixer testing

* Use GitHub Actions to run a suite of tests
* Switch from nose to pytest (nose has not been supported in years)
* Download a PDB file and track it instead of fetching it during CI
  (RCSB has blocked testing frameworks in the past).

* Add missing environment.yaml file

* Try the workflow on my branch

* Try to fix the pipeline

* Stop building on jms-updates