Update GitHub Actions workflows. (#490)

This PR was automatically generated by the
update-workflows-ecosystem-providers workflow in the pulumi/ci-mgmt
repo, from commit fa568f541bd7889bec4c631075aa9f9556cce70b.

upstream.sh

@@ -186,6 +186,8 @@ init() {
   fi
 
   git submodule update --force --init
+  cd upstream && git clean -fxd && cd ..
+
   if [[ "${force}" == "true" ]]; then
     clean_rebases
     clean_branches