ci(github): update pull request template (ethereum#349)

* chore(github): update pull request template

* Update pull_request_template.md

.github/pull_request_template.md

@@ -3,10 +3,32 @@
 ...
 
 
-## 2. Deployment tag versioning
+## 2. PR title
+
+Your PR title must follow [conventional commits](https://www.conventionalcommits.org/en/v1.0.0/#summary) (as we are doing squash merge for each PR), so it must start with one of the following [types](https://github.com/angular/angular/blob/22b96b9/CONTRIBUTING.md#type):
+
+- [ ] build: Changes that affect the build system or external dependencies (example scopes: yarn, eslint, typescript)
+- [ ] ci: Changes to our CI configuration files and scripts (example scopes: vercel, github, cypress)
+- [ ] docs: Documentation-only changes
+- [ ] feat: A new feature
+- [ ] fix: A bug fix
+- [ ] perf: A code change that improves performance
+- [ ] refactor: A code change that doesn't fix a bug, or add a feature, or improves performance
+- [ ] style: Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)
+- [ ] test: Adding missing tests or correcting existing tests
+
+
+## 3. Deployment tag versioning
 
 Has the version in `params/version.go` been updated?
 
 - [ ] This PR doesn't involve a new deployment, git tag, docker image tag, and it doesn't affect traces
 - [ ] Yes
 
+
+## 4. Breaking change label
+
+Does this PR have the `breaking-change` label?
+
+- [ ] This PR is not a breaking change
+- [ ] Yes