Update dependency fs-extra to v11 (postcss#447)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

package.json

@@ -20,7 +20,7 @@
   "dependencies": {
     "chokidar": "^3.3.0",
     "dependency-graph": "^0.11.0",
-    "fs-extra": "^10.0.0",
+    "fs-extra": "^11.0.0",
     "get-stdin": "^9.0.0",
     "globby": "^13.0.0",
     "picocolors": "^1.0.0",