fix: examples/with-atlaskit/package.json to reduce vulnerabilities (#84)

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-POSTCSS-1090595
- https://snyk.io/vuln/SNYK-JS-POSTCSS-1255640

Author: snyk-bot

examples/with-atlaskit/package.json

@@ -13,7 +13,7 @@
     "@atlaskit/datetime-picker": "^9.2.8",
     "@atlaskit/dropdown-menu": "^9.0.2",
     "@atlaskit/field-base": "^14.0.2",
-    "next": "^9.3.1",
+    "next": "^10.2.0",
     "react": "^16.13.1",
     "react-dom": "^16.13.1",
     "styled-components": "^5.0.1"