Bump chan-signal from 0.1.7 to 0.3.3

Bumps [chan-signal](https://github.com/BurntSushi/chan-signal) from 0.1.7 to 0.3.3.
- [Release notes](https://github.com/BurntSushi/chan-signal/releases)
- [Commits](BurntSushi/chan-signal@0.1.7...0.3.3)

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

Author: dependabot-preview[bot]

Cargo.lock

@@ -11,7 +11,7 @@ license = "GPLv3"
 irc = "0.13"
 clap = "2"
 chan = "~0.1.0"
-chan-signal = "~0.1.0"
+chan-signal = "~0.3.3"
 log = "0.3"
 env_logger = "0.7"
 isatty = "0.1"