fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-MARKDOWNTOJSX-6258886

Author: snyk-bot

package.json

@@ -8,7 +8,7 @@
     "connected-react-router": "^6.8.0",
     "dayjs": "^1.10.4",
     "i18next": "^19.4.2",
-    "markdown-to-jsx": "^6.11.4",
+    "markdown-to-jsx": "^7.4.0",
     "moment": "^2.24.0",
     "pigeon-maps": "^0.15.0",
     "pigeon-marker": "^0.3.4",