fix: pin @types/sinon-chai to 3.2.0

Author: greenkeeper[bot]

package.json

@@ -23,7 +23,7 @@
     "@types/react-dom": "^16.0.9",
     "@types/react-test-renderer": "^16.0.3",
     "@types/sinon": "^5.0.5",
-    "@types/sinon-chai": "^3.2.0",
+    "@types/sinon-chai": "3.2.0",
     "@types/webpack": "^4.4.19",
     "coveralls": "^3.0.2",
     "fork-ts-checker-webpack-plugin": "^0.4.15",