meta: update pull request template (#4803)

* resolves: #4796
* resolves: PY-1841

Author: dingsdax

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,7 +1,14 @@
-<!-- Describe your PR here -->
+### Description
+<!-- What changed and why? -->
 
----
+#### Issues
+<!--
+* resolves: #1234
+* resolves: LIN-1234
+-->
 
-Thank you for contributing to `sentry-python`! Please add tests to validate your changes, and lint your code using `tox -e linters`.
-
-Running the test suite on your PR might require maintainer approval.
+#### Reminders
+- Please add tests to validate your changes, and lint your code using `tox -e linters`.
+- Add GH Issue ID _&_ Linear ID (if applicable)
+- PR title should use [conventional commit](https://develop.sentry.dev/engineering-practices/commit-messages/#type) style (`feat:`, `fix:`, `ref:`, `meta:`)
+- For external contributors: [CONTRIBUTING.md](../CONTRIBUTING.md), [Sentry SDK development docs](https://develop.sentry.dev/sdk/), [Discord community](https://discord.gg/Ww9hbqr)