Update GitHub Actions to use AUTO_MERGE_PAT for token authentication

Author: max-ostapenko

.github/workflows/lintsql.yml

@@ -66,4 +66,4 @@ jobs:
         run: gh pr merge --admin --squash "$PR_URL"
         env:
           PR_URL: ${{github.event.pull_request.html_url}}
-          GH_TOKEN: ${{secrets.GITHUB_TOKEN}}
+          GH_TOKEN: ${{secrets.AUTO_MERGE_PAT}}

.github/workflows/test_website.yml

@@ -98,4 +98,4 @@ jobs:
         run: gh pr merge --squash --auto "$PR_URL"
         env:
           PR_URL: ${{github.event.pull_request.html_url}}
-          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}
+          GITHUB_TOKEN: ${{ secrets.AUTO_MERGE_PAT }}