build(deps): bump subtle from 2.3.0 to 2.4.0

Bumps [subtle](https://github.com/dalek-cryptography/subtle) from 2.3.0 to 2.4.0.
- [Release notes](https://github.com/dalek-cryptography/subtle/releases)
- [Changelog](https://github.com/dalek-cryptography/subtle/blob/master/CHANGELOG.md)
- [Commits](https://github.com/dalek-cryptography/subtle/compare/2.3.0...2.4.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Cargo.lock

@@ -1659,9 +1659,9 @@ checksum = "8ea5119cdb4c55b55d432abb513a0429384878c15dde60cc77b1c99de1a95a6a"
 
 [[package]]
 name = "subtle"
-version = "2.3.0"
+version = "2.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "343f3f510c2915908f155e94f17220b19ccfacf2a64a2a5d8004f2c3e311e7fd"
+checksum = "1e81da0851ada1f3e9d4312c704aa4f8806f0f9d69faaf8df2f3464b4a9437c2"
 
 [[package]]
 name = "syn"