chore(deps): bump serial_test from 3.5.0 to 4.0.1

[dependabot]

Bumps serial_test from 3.5.0 to 4.0.1.

Release notes

Sourced from serial_test's releases.

v4.0.1

As per v4.0.0, but with the root MSRV correctly set to 1.93.1

v4.0.0

What's Changed

• MSRV is now 1.93.1
• refactor(derive)!: bump syn to v3 by @​AudaciousAxiom in palfrey/serial_test#159

New Contributors

• @​AudaciousAxiom made their first contribution in palfrey/serial_test#159

Full Changelog: palfrey/serial_test@v3.5.0...v4.0.0

Commits

• 383c894 4.0.1
• 4298adf MSRV is actually 1.93.1
• f25d56f 4.0.0
• 7984bdc Merge pull request #160 from palfrey/pre-release-fixes
• ec74212 Don't need to split build-all-features now
• 03cd910 Upgrade MSRV to 1.93.1
• 7cf8563 Add a "finish" CI job that depends on everything
• d7c4137 Upgrade actix-macros to reduce syn 1.x needs
• ae268b0 Merge pull request #159 from AudaciousAxiom/refactor/syn-v3
• 98b2c36 refactor(derive): bump syn to v3
• Additional commits viewable in compare view

Note
Automatic rebases have been disabled on this pull request as it has been open for over 30 days.

[Tuntii]

Held on purpose during repo hygiene (2026-09-05). This is a major/breaking bump, not a drive-by merge. We'll take it in a dedicated PR after main is green again (#266). Please don't squash-merge this as-is.

[Tuntii]

Superseded by #270 (single lockfile PR for all remaining majors). Closing this Dependabot bump.

[dependabot]

OK, I won't notify you again about this release, but will get in touch when a new version is available. If you'd rather skip all updates until the next major or minor version, let me know by commenting @dependabot ignore this major version or @dependabot ignore this minor version. You can also ignore all major, minor, or patch releases for a dependency by adding an ignore condition with the desired update_types to your config file.

If you change your mind, just re-open this PR and I'll resolve any conflicts on it.