perf: change to cosmiconfig

Author: Scrum

package.json

@@ -33,12 +33,11 @@
     "cli"
   ],
   "dependencies": {
-    "deep-assign": "^3.0.0",
+    "cosmiconfig": "^5.2.1",
     "fast-glob": "^3.0.2",
-    "get-cff": "^0.1.4",
     "make-dir": "^3.0.0",
     "meow": "^5.0.0",
-    "path-exists": "^4.0.0",
+    "merge-options": "^1.0.1",
     "posthtml": "^0.11.4",
     "to-camel-case": "^1.0.0"
   },
@@ -119,7 +118,9 @@
     ]
   },
   "posthtml": {
-    "customElements": {}
+    "plugins": {
+      "posthtml-custom-elements": {}
+    }
   },
   "clinton": {
     "ignores": [