update to react 17, add test with react 16

Author: goto-bus-stop

.travis.yml

@@ -5,3 +5,9 @@ node_js:
   - "stable"
   - "12"
   - "10"
+
+jobs:
+  include:
+    - node_js: 12
+      before_script:
+        npm install react@16 react-test-renderer@16

package.json

@@ -13,8 +13,8 @@
     "react": ">= 16.8.0"
   },
   "devDependencies": {
-    "react": "^16.9.0",
-    "react-test-renderer": "^16.9.0",
+    "react": "^17.0.0",
+    "react-test-renderer": "^17.0.0",
     "rollup": "^2.0.1",
     "rollup-plugin-buble": "^0.19.8",
     "tape": "^5.0.1"