use github token instead + update text

.github/workflows/first_time_contrib.yml

@@ -2,8 +2,11 @@ name: First time contributors
 
 on:
   pull_request_target:
-    types:
-      - opened
+
+permissions:
+  contents: "write"
+  id-token: "write"
+  pull-requests: "write"
 
 jobs:
   comment:
@@ -12,10 +15,8 @@ jobs:
     steps:
       - uses: actions/[email protected]
         with:
-          repo-token: ${{ secrets.RERUN_BOT_TOKEN }}
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
           pr-message: |
             Hi! Thanks for opening this pull request.
 
-            Because this is your first time contributing to this repository, make sure you've read our
-            [Contributor Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md)
-            and [Code of Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md).
+            Because this is your first time contributing to this repository, make sure you've read our [Contributor Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and [Code of Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md).