Add react/react-dom dependencies to relative-paths test fixture (#6165)

Author: ianschmitz

test/fixtures/relative-paths/package.json

@@ -1,4 +1,7 @@
 {
-  "dependencies": {},
+  "dependencies": {
+    "react": "latest",
+    "react-dom": "latest"
+  },
   "homepage": "."
 }