CI: drop the chmod step that the tree check flags

The scripts it made executable are run as `sh ./scripts/diff.sh` and
`node scripts/postbuild-cleanup.cjs`; the mode change only left the
tree dirty, and the new tree check fails on that.

.github/workflows/pr-any.yml

@@ -14,8 +14,6 @@ jobs:
     - uses: actions/setup-node@v4
       with:
         node-version: 'lts/*'
-    - name: Set Execute Permissions
-      run: chmod +x ./scripts/*
     - name: ${{ matrix.step }}
       run: |
         corepack enable