yarn: Upgrade packages

- react: 16.13.1
- react-admin: 3.4.0
- prettier: 2.0.0

Change-Id: Ibbd4ff2bd8054a7086d194229ec732c1a256579c

.prettierrc

@@ -6,5 +6,6 @@
   "singleQuote": false,
   "trailingComma": "es5",
   "bracketSpacing": true,
-  "jsxBracketSameLine": false
+  "jsxBracketSameLine": false,
+  "arrowParens": "avoid",
 }

package.json

@@ -10,22 +10,22 @@
   },
   "devDependencies": {
     "@testing-library/jest-dom": "^5.1.1",
-    "@testing-library/react": "^9.4.0",
-    "@testing-library/user-event": "^8.1.0",
+    "@testing-library/react": "^10.0.2",
+    "@testing-library/user-event": "^10.0.1",
     "enzyme": "^3.11.0",
     "enzyme-adapter-react-16": "^1.15.2",
     "eslint": "^6.8.0",
-    "eslint-config-prettier": "^6.10.0",
+    "eslint-config-prettier": "^6.10.1",
     "eslint-plugin-prettier": "^3.1.2",
-    "prettier": "^1.19.1"
+    "prettier": "^2.0.0"
   },
   "dependencies": {
     "prop-types": "^15.7.2",
     "ra-language-german": "^2.1.2",
-    "react": "^16.12.0",
-    "react-admin": "^3.1.3",
-    "react-dom": "^16.12.0",
-    "react-scripts": "^3.3.0"
+    "react": "^16.13.1",
+    "react-admin": "^3.4.0",
+    "react-dom": "^16.13.1",
+    "react-scripts": "^3.4.1"
   },
   "scripts": {
     "start": "react-scripts start",

src/synapse/dataProvider.js

@@ -141,13 +141,7 @@ const dataProvider = {
 
     return jsonClient(url).then(({ headers, json }) => ({
       data: json,
-      total: parseInt(
-        headers
-          .get("content-range")
-          .split("/")
-          .pop(),
-        10
-      ),
+      total: parseInt(headers.get("content-range").split("/").pop(), 10),
     }));
   },