fix: resolve merge-approved-pr action path for cross-repo workflow calls (#224)

When metamask-mobile calls this reusable workflow, the relative path
`./.github/actions/merge-approved-pr` resolves to the calling repo
(metamask-mobile) instead of github-tools, causing the workflow to fail.

Replace with an absolute ref so the action is always resolved correctly.

Made-with: Cursor

Author: chloeYue

.github/workflows/merge-approved-pr.yml

@@ -38,7 +38,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Merge approved PR
-        uses: ./.github/actions/merge-approved-pr
+        uses: MetaMask/github-tools/.github/actions/merge-approved-pr@v1
         with:
           pr-number: ${{ inputs.pr-number }}
           required-base-branch: ${{ inputs.required-base-branch }}