fix file name

Cargo.toml

@@ -9,7 +9,7 @@ description = "A CATS Igate for moving packets between RF and FELINET. Also hand
 [package.metadata.deb]
 assets = [
        ["target/release/cats-igate", "usr/bin/", "755"],
-       ["debian/cats_igate.service", "/lib/systemd/system/cats_igate.service", "644"],
+       ["debian/cats-igate.service", "/lib/systemd/system/cats-igate.service", "644"],
        ["config.example.toml", "/etc/cats_igate/config.toml", "644"]
 ]
 conf-files = ["/etc/cats_igate/config.toml"]