[cosmos] Update dev dependency "typedoc"

[mikeharder]

Script npm run docs completes without error, but I'm not sure if the doc content needs to be verified as well.

D:\Git\js-mh\sdk\cosmosdb\cosmos>npm run docs

> @azure/[email protected] docs D:\Git\js-mh\sdk\cosmosdb\cosmos
> typedoc --excludePrivate --mode file --out ./dist/docs ./src


Using TypeScript 3.9.3 from D:\Git\js-mh\common\temp\node_modules\.pnpm\registry.npmjs.org\typescript\3.9.3\node_modules\typescript\lib
Rendering [========================================] 100%

Documentation generated at D:\Git\js-mh\sdk\cosmosdb\cosmos\dist\docs

Also, this is the only package in the repo which has a dev dependency on typedoc. Docs for other packages are generated via a dedicated pipeline and tool which depends on typedoc:

https://github.com/Azure/azure-sdk-for-js/tree/de8499ebef11d32836dc652bd1ef6e71323d1bc8/eng/tools/generate-doc
https://github.com/Azure/azure-sdk-for-js/blob/de8499ebef11d32836dc652bd1ef6e71323d1bc8/eng/pipelines/docs.yml

Does cosmos use this doc pipeline yet? If so, maybe the typedoc dev dependency could be removed?

CC: @KarishmaGhiya, @willmtemple

[mikeharder]

Closing since the JS team is owning dependency updates going forward. CC: @ramya-rao-a