chore(deps): update postcss, trim (#3356)

lib/vscode/package.json

@@ -127,7 +127,8 @@
     "copy-webpack-plugin": "^6.0.3",
     "cson-parser": "^1.3.3",
     "css-loader": "^3.2.0",
-    "cssnano": "^4.1.11",
+    "cssnano": "^5.0.2",
+    "postcss": "^8.2.1",
     "debounce": "^1.0.0",
     "deemon": "^1.4.0",
     "eslint": "6.8.0",
@@ -220,6 +221,7 @@
     "windows-process-tree": "0.3.0"
   },
   "resolutions": {
+    "postcss": "^8.2.1",
     "elliptic": "^6.5.3",
     "nwmatcher": "^1.4.4"
   }