client/web: move postcss config into package.json

A little cleanup.

Updates #10261

Signed-off-by: Sonia Appasamy <sonia@tailscale.com>

client/web/package.json

@@ -59,5 +59,11 @@
   "prettier": {
     "semi": false,
     "printWidth": 80
+  },
+  "postcss": {
+    "plugins": {
+      "tailwindcss": {},
+      "autoprefixer": {}
+    }
   }
 }

client/web/postcss.config.js

@@ -1,6 +0,0 @@
-module.exports = {
-  plugins: {
-    tailwindcss: {},
-    autoprefixer: {},
-  },
-}