build(css): Race condition fix for sometimes broken minified css builds

Wait for the uncompressed build to complete before gathering .css files
 for the packed .min.css file.

Author: das7pad

tasks/build/css.js

@@ -140,8 +140,11 @@ function buildCSS(src, type, config, opts, callback) {
   packCompressed.displayName = 'Packing compressed CSS';
 
   gulp.parallel(
-    gulp.series(buildUncompressed, packUncompressed),
-    gulp.series(buildCompressed, packCompressed)
+    gulp.series(
+      buildUncompressed,
+      gulp.parallel(packUncompressed, packCompressed)
+    ),
+    gulp.series(buildCompressed)
   )(callback);
 }