Add pull request template

Author: kderme

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,28 @@
+# Description
+
+Add your description here, if it fixes a particular issue please provide a
+[link](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=)
+to the issue.
+
+# Checklist
+
+- [ ] Commit sequence broadly makes sense
+- [ ] Commits have useful messages
+- [ ] New tests are added if needed and existing tests are updated
+- [ ] Any changes are noted in the
+[changelog](https://github.com/input-output-hk/cardano-db-sync/blob/master/cardano-db-sync/CHANGELOG.md)
+- [ ] Code is formatted with [`fourmolu`](https://github.com/fourmolu/fourmolu)
+(which can be run with `scripts/fourmolize.sh`
+- [ ] Self-reviewed the diff
+
+# Migrations
+
+- [ ] The pr causes a
+[breaking change](https://github.com/input-output-hk/cardano-db-sync/blob/master/doc/migrations.md)
+of type a,b or c
+- [ ] If there is a breaking change, the pr includes a database migration and/or a fix process for
+old values, so that upgrade is possible
+- [ ] Resyncing and running the migrations provided will result in the same database semantically
+
+If there is a breaking change, especially a big one, please add a justification here. Please elaborate
+more what the migration achieves, what it cannot achieve or why a migration is not possible.