Bump react-ga from 2.5.7 to 2.6.0 (#3339)

Bumps [react-ga](https://github.com/react-ga/react-ga) from 2.5.7 to 2.6.0.
- [Release notes](https://github.com/react-ga/react-ga/releases)
- [Commits](react-ga/react-ga@v2.5.7...2.6.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -61,7 +61,7 @@
     "prop-types": "^15.7.2",
     "react": "^16.8.6",
     "react-dom": "^16.8.6",
-    "react-ga": "2.5.7",
+    "react-ga": "2.6.0",
     "shx": "^0.3.2",
     "webpack": "^4.35.2",
     "webpack-cli": "^3.3.1",