fix: pin pydantic to < 2.10 and restore cwd when building bento

[frostming]

Signed-off-by: Frost Ming me@frostming.com

What does this PR address?

Fixes #(issue)

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[aarnphm]

what was the issue for this?

[frostming]

what was the issue for this?

When we build bento in Python code, it should better restore the cwd or it may cause problems, especially when the build ctx is a temp dir and gets destroyed after done.