Update clsx requirement in /packages/material-ui-docs (#45)

Updates the requirements on [clsx](https://github.com/lukeed/clsx) to permit the latest version.
- [Release notes](https://github.com/lukeed/clsx/releases)
- [Commits](lukeed/clsx@v1.0.2...v1.0.4)

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

packages/material-ui-docs/package.json

@@ -39,7 +39,7 @@
   "dependencies": {
     "@babel/runtime": "^7.2.0",
     "@material-ui/utils": "^4.1.0",
-    "clsx": "^1.0.2",
+    "clsx": "^1.0.4",
     "marked": "^0.7.0",
     "nprogress": "^0.2.0",
     "prismjs": "^1.17.1"