Update dependency css-loader to v5

Author: renovate-bot

package-lock.json

@@ -63,7 +63,7 @@
     "@wordpress/block-library": "2.26.3",
     "babel-loader": "8.1.0",
     "browserify-transform-tools": "1.7.0",
-    "css-loader": "4.3.0",
+    "css-loader": "5.0.1",
     "cssnano": "4.1.10",
     "cypress": "5.6.0",
     "eliminate": "1.1.2",