Bump ctrlc from 3.2.5 to 3.4.0 in /src/agent

Bumps [ctrlc](https://github.com/Detegr/rust-ctrlc) from 3.2.5 to 3.4.0.
- [Release notes](https://github.com/Detegr/rust-ctrlc/releases)
- [Commits](Detegr/rust-ctrlc@3.2.5...3.4.0)

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

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

Author: dependabot[bot]

src/agent/Cargo.lock

@@ -6,6 +6,6 @@ authors = ["fuzzing@microsoft.com"]
 edition = "2018"
 
 [dependencies]
-ctrlc = "3.2.3"
+ctrlc = "3.4.0"
 lazy_static = "1.4"
 log = "0.4"