If there's a {{ pr-build-summary }} in the PR description, update i…

…t. (#1971)

* If there's a `{{ pr-build-summary }}`  in the PR description, update it.

* Add comment to the PR template

* Add pull-requests permission to pr_summary job

.github/pull_request_template.md

@@ -15,3 +15,6 @@ To get an auto-generated PR description you can put "copilot:summary" or "copilo
 ### Checklist
 * [ ] I have read and agree to [Contributor Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and the [Code of Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
 * [ ] I've included a screenshot or gif (if applicable)
+
+<!-- This line will get updated when the PR build summary job finishes. -->
+PR Build Summary: {{ pr-build-summary }}

.github/workflows/reusable_pr_summary.yml

@@ -21,6 +21,7 @@ jobs:
     permissions:
       contents: "read"
       id-token: "write"
+      pull-requests: "write"
 
     runs-on: ubuntu-latest
 

scripts/generate_pr_summary.py

@@ -79,6 +79,11 @@ def generate_pr_summary(github_token: str, github_repository: str, pr_number: in
         print("Uploading results to {}".format(upload_blob.name))
         upload_blob.upload_from_file(buffer, content_type="text/html")
 
+        # If there's a {{ pr-build-summary }} string in the PR description, replace it with a link to the summary page.
+        pr_description = pull.body
+        new_description = pr_description.replace("{{ pr-build-summary }}", f"https://build.rerun.io/pr/{pr_number}")
+        pull.edit(body=new_description)
+
 
 def main() -> None:
     parser = argparse.ArgumentParser(description="Generate a PR summary page")