added internal merge/release template

Author: Grochocinski

.github/PULL_REQUEST_TEMPLATE/internal.md

@@ -0,0 +1,24 @@
+---
+name: Release / Internal Merge
+about: Merge `dev` -> `master` (Release), `hotfix` -> `master` (Hotfix), or `master` -> `dev` (Sync)
+title: "[<RELEASE TYPE>] <Version # or Description>"
+labels: "internal"
+---
+
+**INTERNAL USE ONLY**
+
+## Release Type
+- [ ] **Release:** Merging `dev` into `master`
+- [ ] **Hotfix:** Merging `hotfix` into `master`
+- [ ] **Sync:** Back-merging `master` into `dev`
+
+## Summary
+A brief description of the changes made in this PR.
+
+## Versioning & Metadata
+- [ ] Bumped version in `pyproject.toml`
+- [ ] Bumped version in `docs/source/conf.py`
+- [ ] Bumped version in `CITATION.cff`
+
+## Post-Merge Reminder
+- [ ] After merging, create a new GitHub Release / Tag matching the version number.

.github/pull_request_template.md

@@ -3,4 +3,5 @@ Please go to the `Preview` tab and select the appropriate sub-template:
 * [Bug Fix](?expand=1&template=bug_fix.md)
 * [Enhancement](?expand=1&template=enhancement.md)
 * [New Model/Problem](?expand=1&template=new_model_problem.md)
-* [New Solver](?expand=1&template=new_solver.md)
+* [New Solver](?expand=1&template=new_solver.md)
+* [Release/Internal Merge (Internal Use Only)](?expand=1&template=internal.md)