chore(deps): update dependency gulp-clean-css to ~4.3.0

Author: renovate[bot]

package-lock.json

@@ -59,7 +59,7 @@
     "eslint-plugin-import": "~2.18.0",
     "gulp": "~4.0.2",
     "gulp-autoprefixer": "^7.0.0",
-    "gulp-clean-css": "~4.2.0",
+    "gulp-clean-css": "~4.3.0",
     "gulp-eslint": "~6.0.0",
     "gulp-newer": "~1.4.0",
     "gulp-rename": "~1.4.0",