Fix: Update markdown-to-jsx (#1599)

This updates the markdown-to-jsx package to v6.11.4 in order to patch a security vulnerability as reported at #1596 and addressed here at quantizor/markdown-to-jsx#306

Author: Kyle Decker

package-lock.json

@@ -65,7 +65,7 @@
     "loader-utils": "^2.0.0",
     "lodash": "^4.17.15",
     "lowercase-keys": "^2.0.0",
-    "markdown-to-jsx": "^6.10.3",
+    "markdown-to-jsx": "^6.11.4",
     "mini-html-webpack-plugin": "^2.0.0",
     "mri": "^1.1.4",
     "ora": "^4.0.2",