add PR test workflow and issue templates

[Tieqiong]

@sbillinge please check. This is a temporary pr-test workflow running unit test. Will update during cookie cut.

[Tieqiong]

Seems like we need to initialize the action by setting up some kind of Github workflow on main... Or maybe it's some permission issue?

[sbillinge]

Add cookie to branches in the test on pr workflow and it should ten the tests

[Tieqiong]

@sbillinge I don't think that's the issue because we have pull_request listed. Also see #40 which also can't trigger the action

[bobleesj]

@Tieqiong Maybe you could confirm whether it's a permission problem by making a PR to your own main?

[Tieqiong]

@bobleesj I tried it on my side, and this is why I was suggesting initializing action by workflow on main. However I'm not sure if it would be the same for organizational repo

[bobleesj]

Yup, seems like it stems from permission

PR to origin/main runs tests-on-pr https://github.com/bobleesj/diffpy.srreal/pull/1
PR to upstream/main does NOT run tests-on-pr #41

[sbillinge]

I will mege this and we can see if it runs the CI on push

[sbillinge]

so it seems that tests-on-pr ran ok when I merged to main. Let's assume everything is ok, and see if it just fixes itself next time. I vaguely remember similar issues like this before that just went away after the first merge.