fix: Clean up package.json

+ Remove packages that duplicate node core modules: fs, path
+ Remove unused package "concurrently". If required in the future,
  use the & of your shell instead.
+ Remove unused package "postcss-plugin" — not used and does not
  provide any features.
+ Move tailwind plugins into devDependencies

.postcssrc.json

@@ -2,7 +2,6 @@
   "map": false,
   "plugins": {
     "tailwindcss": {},
-    "postcss-plugin": {},
     "autoprefixer": {},
     "postcss-pxtorem": {}
   }

package.json

@@ -10,13 +10,11 @@
   },
   "devDependencies": {
     "@tailwindcss/aspect-ratio": "^0.4.2",
+    "@thoughtbot/tailwindcss-aria-attributes": "^0.2.0",
     "@types/alpinejs": "^3.7.1",
+    "@types/node": "^20.2.5",
     "autoprefixer": "^10.4.14",
-    "concurrently": "^7.6.0",
-    "fs": "0.0.1-security",
-    "path": "^0.12.7",
     "postcss": "^8.4.24",
-    "postcss-plugin": "^1.0.0",
     "postcss-pxtorem": "^6.0.0",
     "sass": "^1.62.1",
     "tailwindcss": "^3.3.2",
@@ -27,7 +25,6 @@
   },
   "packageManager": "yarn@3.5.0",
   "dependencies": {
-    "@thoughtbot/tailwindcss-aria-attributes": "^0.2.0",
     "alpinejs": "^3.12.2"
   }
 }