Update dependencies + bump version.

Author: brocaar

Cargo.lock

@@ -2,13 +2,13 @@
 name = "chirpstack-udp-forwarder"
 repository="https://github.com/chirpstack/chirpstack-udp-forwarder/"
 license="MIT"
-version = "4.0.0-test.2"
+version = "4.0.0-rc.1"
 authors = ["Orne Brocaar <info@brocaar.com>"]
 edition = "2018"
 publish = false
 
 [dependencies]
-chirpstack_api = { version = "4.0.0-test.18", default-features = false }
+chirpstack_api = { version = "4.0.0-rc.1", default-features = false }
 serde_json = "1.0"
 zmq = "0.9"
 clap = "3.2"