Loosen dependency

Author: jxnblk

packages/mdx/package.json

@@ -11,7 +11,7 @@
   "dependencies": {
     "@emotion/core": "^10.0.0",
     "@emotion/styled": "^10.0.0",
-    "@mdx-js/react": "^1.5.1"
+    "@mdx-js/react": "^1.0.0"
   },
   "peerDependencies": {
     "@theme-ui/core": "*",