fix(ci): mark workspace safe for git in mise-lockfile job

Signed-off-by: Piotr Mlocek <pmlocek@nvidia.com>

Author: pimlock

.github/workflows/branch-checks.yml

@@ -24,6 +24,9 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - name: Mark workspace as safe for git
+        run: git config --global --add safe.directory "$GITHUB_WORKSPACE"
+
       - name: Verify mise.lock is in sync with mise.toml
         run: |
           mise lock