Lower MSRV to 1.75

[tiran]

Change Summary

Lower MSRV to 1.75. Rust 1.75 is the lowest working Rust version.

Related issue number

fix: #1315

Checklist

• Unit tests for the changes exist
• Documentation reflects the changes where applicable
• Pydantic tests pass with this pydantic-core (except for expected changes)
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

Selected Reviewer: @samuelcolvin

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

📢 Thoughts on this report? Let us know!

[tiran]

please review

MSRV is not mentioned in README.md and there are no tests beyond the "test MSRV" job. Lowering MSRV should not have an impact on pydantic tests, either.

[codspeed-hq]

CodSpeed Performance Report

Merging #1316 will not alter performance

_{Comparing tiran:lower-msrv (9f2014d) with main (77f2b69)}

Summary

✅ 155 untouched benchmarks

[davidhewitt]

Thanks, agreed! I think in my head I needed return-position-impl-trait-in-trait from 1.76, but you're right this came in 1.75 🙈

For what it's worth it would be possible to make <1.75 work, but it'd be a lot more effort.