fix PR template

Signed-off-by: Danny Chiao <danny@tecton.ai>

Author: adchia

.github/pull_request_template.md

@@ -5,6 +5,7 @@
 3. If your change introduces any API changes, make sure to update the integration tests here: https://github.com/feast-dev/feast/tree/master/sdk/python/tests
 4. Make sure documentation is updated for your PR!
 5. Make sure your commits are signed: https://github.com/feast-dev/feast/blob/master/CONTRIBUTING.md#signing-off-commits
+6. Make sure your PR title follows conventional commits (e.g. fix: [description] vs feat: [description])
 
 -->