Update dependency rollup-plugin-css-only to v4

Author: renovate[bot]

package-lock.json

@@ -49,7 +49,7 @@
     "rollup": "2.78.1",
     "rollup-plugin-buble": "0.19.8",
     "rollup-plugin-commonjs": "10.1.0",
-    "rollup-plugin-css-only": "3.1.0",
+    "rollup-plugin-css-only": "4.5.2",
     "rollup-plugin-node-resolve": "5.2.0",
     "rollup-plugin-replace": "2.2.0",
     "rollup-plugin-terser": "5.3.1",