fix: clear checkout extraheader before pushing submodule tag

The actions/checkout configures a global http.extraheader that overrides
URL-embedded credentials. Clear it before pushing to ReScene.Lib.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: NeWbY100

.github/workflows/release.yml

@@ -60,6 +60,7 @@ jobs:
           SUBMODULE_SHA=$(git rev-parse HEAD)
           TAG="v${{ steps.version.outputs.version }}"
           echo "Tagging ReScene.Lib commit $SUBMODULE_SHA as $TAG"
+          git config --unset-all http.https://github.com/.extraheader || true
           git tag "$TAG" "$SUBMODULE_SHA"
           git remote set-url origin "https://x-access-token:${LIB_PAT}@github.com/NeWbY100/ReScene.Lib.git"
           git push origin "$TAG"