Update peter-evans/create-pull-request action to v8

Author: renovate[bot]

.github/workflows/gt-update.yml

@@ -149,7 +149,7 @@ jobs:
       - name: Create pull request if necessary
         if: ${{ steps.has_changes.outputs.has_changes == 1 }}
         #gt-placeholder-gh-action-create-pr-start
-        uses: peter-evans/create-pull-request@v7
+        uses: peter-evans/create-pull-request@v8
         #gt-placeholder-gh-action-create-pr-end
         with:
           branch: 'gt/update/${{ matrix.remote }}'