remove keyword in Cargo.toml due to limit

Author: pzmarzly

Cargo.toml

@@ -5,7 +5,7 @@ description = "Forwards ports on UPnP-enabled gateways. Inspired by portmapper (
 authors = ["Paweł Zmarzły <[email protected]>"]
 homepage = "https://github.com/pzmarzly/portforwarder-rs"
 repository = "https://github.com/pzmarzly/portforwarder-rs"
-keywords = ["upnp", "port", "forwarding", "network", "forward", "ipv4"]
+keywords = ["upnp", "port", "forwarding", "network", "forward"]
 readme = "README.md"
 categories = ["network-programming", "command-line-utilities"]
 license = "MIT"