Bump react-dropzone from 3.7.3 to 9.0.0

Bumps [react-dropzone](https://github.com/react-dropzone/react-dropzone) from 3.7.3 to 9.0.0.
- [Release notes](https://github.com/react-dropzone/react-dropzone/releases)
- [Commits](react-dropzone/react-dropzone@v3.7.3...v9.0.0)

Signed-off-by: dependabot[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

package-lock.json

@@ -172,7 +172,7 @@
     "react-codemirror": "^1.0.0",
     "react-copy-to-clipboard": "5.0.1",
     "react-dom": "15.6.2",
-    "react-dropzone": "3.7.3",
+    "react-dropzone": "9.0.0",
     "react-element-to-jsx-string": "14.0.3",
     "react-event-listener": "0.6.6",
     "react-inspector": "paritytech/react-inspector",