ci: add pull request template from epiprocess

.github/pull_request_template.md

@@ -0,0 +1,21 @@
+### Checklist
+
+Please:
+
+- [ ] Make sure this PR is against "dev", not "main".
+- [ ] Request a review from one of the current epiprocess main reviewers:
+      brookslogan, nmdefries.
+- [ ] Makes sure to bump the version number in `DESCRIPTION` and `NEWS.md`.
+      Always increment the patch version number (the third number), unless you are
+      making a release PR from dev to main, in which case increment the minor
+      version number (the second number).
+- [ ] Describe changes made in NEWS.md, making sure breaking changes
+      (backwards-incompatible changes to the documented interface) are noted.
+      Collect the changes under the next release number (e.g. if you are on
+      1.7.2, then write your changes under the 1.8 heading).
+
+### Change explanations for reviewer
+
+### Magic GitHub syntax to mark associated Issue(s) as resolved when this is merged into the default branch
+
+- Resolves #{issue number}