chore(main): release 5.0.0-alpha.21.0

[github-actions]

🤖 I have created a release beep boop

5.0.0-alpha.21.0 (2025-12-18)

Features

• Add exception types (#173) (72f09b2)
• Add Json static class with Fable-aware serialization (#175) (1eb5005)
• add Python stdlib bindings for logging, random, and expand string module (#166) (709d6c2)
• add write (334e800)
• Added bindings for Pydantic and FastAPI + examples (#151) (826629e)
• Fable v5 (#147) (abf8e6a)
• FastAPI async handlers (#174) (26cec1f)

Bug Fixes

• add missing models.py for pydantic example and update README (#168) (b76ce98)
• handle return type correctly (a634168)
• relax FSharp.Core dependency to >= 5.0.0 (#163) (10eb65b)
• remove versioning strategy from release-please config (ce84cae)
• update pyproject toml details (#62) (b511351)
• update release-please to use prerelease versioning (7c219e8)
• use plain int/string types for open (b202a25)
• use string types for open (f211f8b)

Miscellaneous Chores

• sync with Fable 5.0.0-alpha.21 (fd2685c)

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