Modify PR template to include AI policy checkbox

Updated due diligence checklist for PR submissions.

Author: TobiGr

.github/PULL_REQUEST_TEMPLATE.md

@@ -32,5 +32,5 @@ The APK can be found by going to the "Checks" tab below the title. On the left p
 
 #### Due diligence
 - [ ] I read the [contribution guidelines](https://github.com/TeamNewPipe/NewPipe/blob/HEAD/.github/CONTRIBUTING.md).
-- [ ] The propsed changes are **not AI generated**.
+- [ ] The propsed changes follow the [AI policy](https://github.com/TeamNewPipe/NewPipe/blob/HEAD/.github/CONTRIBUTING.md#use-of-generative-ai).
 - [ ] I tested the changes using an emulator or a physical device.