Update Mermaid to 9.3.0

[znorris]

Upgrade to Mermaid 9.3.0 to support new features https://github.com/mermaid-js/mermaid/releases/tag/v9.3.0.

Thanks for making this extension, very useful!

[mjbvz]

Want to submit a pr for this? It should be pretty straightforward

[apeacock1991]

I've raised a PR here: #165. Strangely npm install doesn't work for me on master (it complaints a lot about deps, particularly mermaid-markdown/webpack etc.) but based on a prior PR these are the only changes required.

[znorris]

@apeacock1991 Thank you for doing this! I had a problem with getting master to build so that's why I didn't go ahead and make a PR. I appreciate this extension @mjbvz and the awesome people that keep it up to date @apeacock1991.