Fix tailwind setup

- Adopted postcss and tailwind config to new version
- renamed colors bluegray->slate etc to not have custom
  definitions (hope to reduce migration next time)
- tailwind now doesn't build the complete css anymore, so the
  `dev-ui-build` script must compile both

modules/webapp/package.json

@@ -6,13 +6,13 @@
   "devDependencies": {
     "@fortawesome/fontawesome-free": "^5.15.4",
     "@tailwindcss/forms": "^0.4.0",
+    "autoprefixer": "^10.4.0",
+    "cssnano": "^5.0.14",
     "flag-icon-css": "^3.5.0",
-    "postcss-cli": "^9.0.1",
+    "postcss": "^8.4.5",
+    "postcss-cli": "^9.1.0",
     "postcss-import": "^14.0.2",
-    "autoprefixer": "^10.3.7",
-    "cssnano": "^5.0.8",
-    "postcss": "^8.3.11",
     "postcss-purgecss": "^2.0.3",
-    "tailwindcss": "^3.0.0"
+    "tailwindcss": "^3.0.7"
   }
 }