fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-CROSSSPAWN-8303230

Author: snyk-bot

package.json

@@ -51,9 +51,9 @@
     "eslint-plugin-react-native": "^4.0.0",
     "eslint-plugin-standard": "^4.0.0",
     "i": "^0.3.5",
-    "jest": "^26.0.1",
+    "jest": "^27.0.0",
     "react": "16.11.0",
-    "react-native": "^0.68.0",
+    "react-native": "^0.75.0",
     "ts-jest": "^26.0.0",
     "typescript": "^3.9.5"
   },