Allow React 17 as a peer dependency

Author: jakezatecky

package.json

@@ -26,7 +26,7 @@
     "test": "gulp test-script"
   },
   "peerDependencies": {
-    "react": "^15.3.0 || ^16.0.0"
+    "react": "^15.3.0 || ^16.0.0 || ^17.0.0"
   },
   "devDependencies": {
     "@babel/core": "^7.0.0",