Release: LangChain 0.3 dev

[efriis]

Hey folks!

The team has been hard at work on a 0.3 release, which will primarily migrate LangChain to Pydantic v2.

In the coming weeks, you'll see some pre-releases of various langchain libraries on pypi. Today, you'll see langchain-core==0.3.0.dev0 as the first release in this series.

These dev releases are primarily for core maintainers' use, as well as folks who manage integrations. These dev releases are not ready for use in your application.

When we're ready for you to start testing a 0.3 version as well as any associated migration scripts, we'll release those as 0.3.0rc versions (not .dev).

Let us know if you have any questions!

[ccurme]

Please see an update on this discussion in a new post here: #26180