dx(pr): setup pull request template

fix #4

.github/pull_request_template.md

@@ -0,0 +1,30 @@
+# Changes
+Put your additions and changes here...
+
+## Resolved issues
+- Closes lemredd/calculator#
+
+## Pull Requests to merge first
+<!--
+Specify unmerged pull requests required before merging this one.
+This is to avoid complicating conflicts.
+-->
+- none / lemredd/calculator#
+
+## Breaking Changes
+- none lemredd/calculator#
+
+## Pull Request Quality
+- Will have additional commits?
+  - [ ] None
+  - [ ] Yes
+  - [ ] Yes, unless all tests are success
+  - [ ] None, unless some tests are failing
+
+## Lacking Mechanism
+- none / lemredd/calculator#
+
+## Proof of Passing
+<!--
+To be setup once tests are configured.
+-->