chore: create PR template

Includes a helpful checklist with reminders such as updating the changelog, which aids the release process

Author: kelly-sovacool

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,21 @@
+## Changes
+
+<!--
+Provide a summary of what is included in this Pull Request (PR).
+-->
+
+## Issues
+
+<!--
+Reference any issues related to this PR.
+If this PR fixes any issues, [use a keyword](https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue#linking-a-pull-request-to-an-issue-using-a-keyword)
+when referring to the issue.
+-->
+
+## PR Checklist
+
+(~Strikethrough~ any points that are not applicable.)
+
+- [ ] This comment contains a description of changes with justifications, with any relevant issues linked.
+- [ ] Update docs if there are any API changes.
+- [ ] Update `CHANGELOG.md` with a short description of any user-facing changes and reference the PR number. Guidelines: https://keepachangelog.com/en/1.1.0/