Handle nested env arg

Author: aybchan

.github/actions/gke-xpk/action.yml

@@ -215,7 +215,7 @@ runs:
         IFS=';' read -ra env_vars <<< "${envs_flat}"
         for env in "${env_vars[@]}"; do
             env=$(echo "${env}" | xargs)
-            [[ -n "${env}" ]] && args+=("--env=${env}")
+            [[ -n "${env}" ]] && args+=("--env='${env}'")
         done
       fi