Update dependency chalk to v4 (postcss#322)

Co-authored-by: Renovate Bot <bot@renovateapp.com>

Author: renovate[bot]

package.json

@@ -18,7 +18,7 @@
     "test": "nyc ava -v"
   },
   "dependencies": {
-    "chalk": "^3.0.0",
+    "chalk": "^4.0.0",
     "chokidar": "^3.3.0",
     "dependency-graph": "^0.9.0",
     "fs-extra": "^9.0.0",