Make markdown links relative and adjust package dependencies slightly

[quantum-byte]

Hi,

really cool package. Improves dbt documentation quite a bit. Thanks for you effort!
I noticed two issues and propose some small general improvements. Please have a look.

1. Fix generated links by making them relative. This way they also work for static dbt documentation under a different root path.

2. Reorganized the dependencies for the project slightly:

   • Made them less restrictive.
     • E.g. newer dbt versions require higher pydantic version (dbt-semantic-interfaces 0.4.1 requires pydantic~=1.10).
     • Btw. Pydantic 2.* might be an issue soon, since it is part of a lot of different libs.
   • Moved google-cloud-storage and requests to a separate setup.py extra cloud-support requirement. They now can be installed additionally and only if the are needed for the cloud functionality.
     • We do not use dbt in the cloud so we do not need those packages by default. I can also revert it, if you dont see the value in that.