[ci] Workaround nightly C++ test crash (taichi-dev#5789)

Author: feisuzhu

.github/workflows/scripts/aot-demo.sh

@@ -18,7 +18,9 @@ function build-and-smoke-test-android-aot-demo {
 
     # Normally we checkout the master's commit Id: https://github.com/taichi-dev/taichi-aot-demo/commit/master
     # As for why we need this explicit commit Id here, refer to: https://docs.taichi-lang.org/docs/master/contributor_guide#handle-special-ci-failures
-    cd taichi-aot-demo && git checkout 82aaecb9224ac24baf4abfdb5e94f1c6edb464c3 && cd -
+    pushd taichi-aot-demo
+    git checkout master
+    popd
 
     APP_ROOT=taichi-aot-demo/implicit_fem
     ANDROID_APP_ROOT=$APP_ROOT/android