fix: upgrade @material-ui/core from 4.11.4 to 4.12.3

Snyk has created this PR to upgrade @material-ui/core from 4.11.4 to 4.12.3.

See this package in npm:
https://www.npmjs.com/package/@material-ui/core

See this project in Snyk:
https://app.snyk.io/org/reactioncommerce/project/536303cd-177f-47dd-aa8b-35217cef374d?utm_source=github&utm_medium=upgrade-pr

package.json

@@ -77,7 +77,7 @@
     "@fortawesome/fontawesome-svg-core": "^1.2.25",
     "@fortawesome/free-solid-svg-icons": "^5.7.1",
     "@fortawesome/react-fontawesome": "^0.1.4",
-    "@material-ui/core": "^4.9.2",
+    "@material-ui/core": "^4.12.3",
     "@material-ui/lab": "^4.0.0-alpha.42",
     "@reactioncommerce/catalyst": "^1.19.1",
     "@reactioncommerce/components": "^0.69.0",