Bump regex from 1.5.6 to 1.9.4 (#3197)

Bumps [regex](https://github.com/rust-lang/regex) from 1.5.6 to 1.9.4.
- [Release notes](https://github.com/rust-lang/regex/releases)
- [Changelog](https://github.com/rust-lang/regex/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-lang/regex/compare/1.5.6...1.9.4)

---
updated-dependencies:
- dependency-name: regex
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

taskchampion/xtask/Cargo.toml

@@ -9,4 +9,4 @@ anyhow.workspace = true
 
 taskchampion-lib = { path = "../lib" }
 
-regex = "^1.5.6"
+regex = "^1.9.4"