Tooling: try to parallelize js builds a bit

plugins/woocommerce/package.json

@@ -11,7 +11,7 @@
 	"license": "GPL-3.0+",
 	"scripts": {
 		"build": "pnpm --if-present --workspace-concurrency=Infinity --stream --filter=\"$npm_package_name...\" '/^build:project:.*$/'",
-		"build:project": "pnpm --if-present '/^build:project:.*$/'",
+		"build:project": "pnpm --if-present --parallel '/^build:project:.*$/'",
 		"build:project:copy-assets": "wireit",
 		"build:zip": "./bin/build-zip.sh",
 		"changelog": "composer install && composer exec -- changelogger",