chore(deps-dev): bump cssnano from 5.1.12 to 5.1.15 (#8432)

Author: dependabot[bot]

package-lock.json

@@ -129,7 +129,7 @@
     "cors": "^2.8.5",
     "cross-env": "=7.0.3",
     "css-loader": "=6.7.1",
-    "cssnano": "=5.1.12",
+    "cssnano": "=5.1.15",
     "cypress": "=9.5.1",
     "dedent": "^0.7.0",
     "deepmerge": "^4.0.0",