chore: Update pull request template (#1294)

Video link was dead.

Co-authored-by: Pete Frisella <pete.frisella@gmail.com>

.github/pull_request_template.md

@@ -1,8 +1,5 @@
 ## 👋👋 Thank you for contributing to Looker sdk-codegen (⚡️🍣)
 
-📺 Watch a quick video on how to you make your pull requests fast and easy for you and your reviewer(s):
-https://threadit.app/thread/k45nyrqugoinw6xub9vf/message/fl8m57exhqg4r0a4hg01eebn
-
 - 👆 Make sure your pull request title follows [Pull Request Title Guidelines](https://github.com/looker-open-source/sdk-codegen/blob/main/CONTRIBUTING.md#title-guidelines) from our [Contribution guide](https://github.com/looker-open-source/sdk-codegen/blob/main//CONTRIBUTING.md)
 - 👉 Don't forget to replace these instructions with your _✨awesome✨_ description of what this change _actually does_. Additionally, it's great to include context on how it works and why the change was needed.
 - 👇 Edit "Developer Checklist" to reflect items relevant to this PR (and try to make sure to check everything off before asking for review)