build(deps): update regex-syntax requirement from 0.6 to 0.7

Updates the requirements on [regex-syntax](https://github.com/rust-lang/regex) to permit the latest version.
- [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/commits)

---
updated-dependencies:
- dependency-name: regex-syntax
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

lib/Cargo.toml

@@ -42,7 +42,7 @@ async-std = "1.12"
 jsonwebtoken = { version = "8.1", default-features = false }
 rand_xorshift = "0.3"
 rand = "0.8"
-regex-syntax = { version = "0.6", default-features = false }
+regex-syntax = { version = "0.7", default-features = false }
 rand_regex = { version = "0.15", default-features = false }
 thiserror = "1.0"
 rand_distr = "0.4"