Bump regex from 1.7.3 to 1.8.1 (#922)

Bumps [regex](https://github.com/rust-lang/regex) from 1.7.3 to 1.8.1.
- [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/1.7.3...1.8.1)

---
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>

testing/integration-tests/Cargo.toml

@@ -21,7 +21,7 @@ codec = { package = "parity-scale-codec", version = "3.0.0", default-features =
 frame-metadata = { version = "15.1.0", features = ["v14", "v15-unstable", "std"] }
 futures = "0.3.27"
 hex = "0.4.3"
-regex = "1.7.3"
+regex = "1.8.1"
 scale-info = { version = "2.5.0", features = ["bit-vec"] }
 sp-core = { version = "20.0.0", default-features = false }
 sp-runtime = "23.0.0"