chore(deps): update peter-evans/create-pull-request action to v8

Author: renovate[bot]

.github/workflows/palette.yml

@@ -27,7 +27,7 @@ jobs:
         run: uv run --extra matplotlib build.py
 
       - name: Create Pull Request
-        uses: peter-evans/create-pull-request@v7
+        uses: peter-evans/create-pull-request@v8
         with:
           commit-message: "feat: auto-sync upstream palettes"
           committer: "GitHub <noreply@github.com>"