fix: upgrade multiple dependencies with Snyk

Snyk has created this PR to upgrade:
  - react from 16.12.0 to 16.13.0.
    See this package in NPM: https://www.npmjs.com/package/react
  - react-dom from 16.12.0 to 16.13.0.
    See this package in NPM: https://www.npmjs.com/package/react-dom

See this project in Snyk:
https://app.snyk.io/org/coderbyheart/project/1ab786f4-04b1-43be-a4da-24473afa5df0?utm_source=github&utm_medium=upgrade-pr

Author: snyk-bot

package-lock.json

@@ -30,8 +30,8 @@
     "@material-ui/icons": "^4.9.1",
     "bootstrap": "^4.4.1",
     "leaflet": "^1.6.0",
-    "react": "^16.12.0",
-    "react-dom": "^16.12.0",
+    "react": "^16.13.0",
+    "react-dom": "^16.13.0",
     "react-leaflet": "^2.6.1",
     "reactstrap": "^8.4.1",
     "styled-components": "^5.0.0",