chore(deps): use postcss 8

.postcssrc

@@ -1,6 +0,0 @@
-{
-  plugins: {
-    "postcss-nested": {},
-    "autoprefixer": {}
-  }
-}

package.json

@@ -35,7 +35,7 @@
     "react-draggable": "^4.4.3"
   },
   "devDependencies": {
-    "@babel/core": "^7.12.7",
+    "@babel/core": "^7.12.9",
     "@babel/plugin-transform-runtime": "^7.12.1",
     "@babel/preset-env": "^7.12.7",
     "@babel/preset-react": "^7.12.7",
@@ -49,17 +49,18 @@
     "@types/react": "^17.0.0",
     "@types/react-dom": "^17.0.0",
     "@types/resize-observer-browser": "^0.1.4",
-    "autoprefixer": "^9.8.6",
+    "autoprefixer": "^10.0.4",
     "babel-preset-react-app": "^10.0.0",
     "cypress": "^6.0.1",
-    "postcss-nested": "^4.2.3",
+    "postcss": "^8.1.14",
+    "postcss-nested": "^5.0.2",
     "prettier": "2.2.1",
     "prop-types": "^15.7.2",
     "react": "^17.0.1",
     "release-it": "^14.2.2",
     "rollup": "^2.34.2",
     "rollup-plugin-bundle-size": "^1.0.3",
-    "rollup-plugin-postcss": "^3.1.8",
+    "rollup-plugin-postcss": "^4.0.0",
     "rollup-plugin-typescript2": "^0.29.0",
     "start-server-and-test": "^1.11.6",
     "typescript": "^4.1.2"

postcss.config.js

@@ -0,0 +1,3 @@
+module.exports = {
+  plugins: [require('autoprefixer'), require('postcss-nested')],
+};