Fix inconsistency between type libraries for markdown-it and linkify-it

[nkohari]

Hey there! 😄

I was updating apocrypha to the latest version of Markdoc and started running into some type errors:

> @apocrypha/core@0.3.0 build:types
> tsc --emitDeclarationOnly --outDir dist

../../node_modules/@types/markdown-it/lib/index.d.ts:151:33 - error TS2694: Namespace '"/Users/nkohari/Work/apocrypha/node_modules/@types/linkify-it/index"' has no exported member 'LinkifyIt'.

151     readonly linkify: LinkifyIt.LinkifyIt;
                                    ~~~~~~~~~

Found 1 error in ../../node_modules/@types/markdown-it/lib/index.d.ts:151

Turns out, this is because @types/markdown-it depends on any version (*) of @types/linkify-it, but the latter wasn't reverse-compatible. This patch pins the version of @types/linkify-it to the one which is compatible with the the version of the actual markdown-it library that Markdoc uses.

Let me know if you have any questions or need more info!

[CLAassistant]

All committers have signed the CLA.

[matv-stripe]

Thanks!