chore(deps): update dependency cssnano to v5.1.15

Author: renovate[bot]

webapp-1/package-lock.json

@@ -29,7 +29,7 @@
     "babel-loader": "9.1.2",
     "copy-webpack-plugin": "11.0.0",
     "css-loader": "6.7.3",
-    "cssnano": "5.1.14",
+    "cssnano": "5.1.15",
     "file-loader": "6.2.0",
     "html-webpack-plugin": "5.5.0",
     "mini-css-extract-plugin": "1.2.1",