Update dependency pdm-backend to v2.4.3

[RKIMetadataExchange]

This PR contains the following updates:

Package	Type	Update	Change
pdm-backend	build-system.requires	patch	==2.4.1 -> ==2.4.3

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Release Notes

pdm-project/pdm-backend (pdm-backend)

v2.4.3

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   💻 Chores

• Bump validate-pyproject to 0.9.0  -  by @​henryiii in https://github.com/pdm-project/pdm-backend/issues/265 (23484)
• Update dependencies  -  by @​frostming (7f7dd)
• Update badge  -  by @​frostming (6fdd4)
• Migrate tool config to pyproject.toml  -  by @​frostming (d5d5c)

    View changes on GitHub

v2.4.2

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   🚀 Features

• Use fallback_version for source = "call"  -  by @​frostming in https://github.com/pdm-project/pdm-backend/issues/264 (16562)

   🐞 Bug Fixes

• Update to pyproject_metadata 0.9.0b5  -  by @​henryiii in https://github.com/pdm-project/pdm-backend/issues/263 (67fb7)

    View changes on GitHub

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