fix: github pull request template (#1687)

Why is this change necessary?

* The previous pull request template just had a section to describe
* changes which was not prescriptive enough to fully understand the
* context

How does it address the issue?

* A series of questions, that need to be answered instead is proposed
* which will help to set context in a more formal manner.

What side effects does this change have?

* None

Co-authored-by: Jacob Fuss <32497805+jfuss@users.noreply.github.com>

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,6 +1,10 @@
 *Issue #, if available:*
 
-*Description of changes:*
+*Why is this change necessary?*
+
+*How does it address the issue?*
+
+*What side effects does this change have?*
 
 *Checklist:*