Bump classnames from 2.2.6 to 2.3.1 in /packages/webapp

Bumps [classnames](https://github.com/JedWatson/classnames) from 2.2.6 to 2.3.1.
- [Release notes](https://github.com/JedWatson/classnames/releases)
- [Changelog](https://github.com/JedWatson/classnames/blob/master/HISTORY.md)
- [Commits](https://github.com/JedWatson/classnames/commits)

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

packages/webapp/package.json

@@ -8,7 +8,7 @@
     "axios": "0.21.1",
     "boolean": "^3.0.2",
     "bytes": "3.1.0",
-    "classnames": "2.2.6",
+    "classnames": "2.3.1",
     "gatsby": "^3.0.4",
     "gatsby-plugin-manifest": "^3.0.0",
     "gatsby-plugin-matomo": "0.9.0",