Update pull_request_template.md

Author: dingsdax

.github/pull_request_template.md

@@ -9,7 +9,7 @@
 
 <!--
 #### Reminders
-- Add GH Issue ID _&_ Linear ID
+- 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)
--->
+-->