[stable31] fix(ci): checkout stable31 branch of context_chat

[kyteinsky]

No description provided.

[kyteinsky]

× Dependency resolution exceeded maximum depth
570
╰─> Pip cannot resolve the current dependencies as the dependency graph is too complex for pip to solve efficiently.
571
hint: Try adding lower bounds to constrain your dependencies, for example: 'package>=2.0.0' instead of just 'package'.
572

this needs a backport of #236