Bump markdown-to-jsx from 6.10.3 to 6.11.4

Bumps [markdown-to-jsx](https://github.com/probablyup/markdown-to-jsx) from 6.10.3 to 6.11.4.
- [Release notes](https://github.com/probablyup/markdown-to-jsx/releases)
- [Commits](quantizor/markdown-to-jsx@6.10.3...6.11.4)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

package-lock.json

@@ -18,7 +18,7 @@
     "gatsby-plugin-styled-components": "^3.0.7",
     "gatsby-source-filesystem": "^2.0.23",
     "gatsby-transformer-sharp": "^2.3.2",
-    "markdown-to-jsx": "^6.9.4",
+    "markdown-to-jsx": "^6.11.4",
     "prop-types": "^15.7.2",
     "react": "^16.8.4",
     "react-dom": "^16.8.4",