docs: update langchain-cloudflare repo/path on packages.yaml (#31138)
**Library Repo Path Update **: "langchain-cloudflare"
We recently changed our `langchain-cloudflare` repo to allow for future
libraries.
Created a `libs` folder to hold `langchain-cloudflare` python package.
https://github.com/cloudflare/langchain-cloudflare/tree/main/libs/langchain-cloudflare
On `langchain`, updating `packages.yaml` to point to new
`libs/langchain-cloudflare` library folder.