Update build dependencies

This needed also some adaption in order to use `clap 3.0.0-rc.0`.

src/cli.rs

@@ -1,4 +1,4 @@
-use clap::{crate_authors, crate_version, AppSettings, Parser};
+use clap::{AppSettings, Parser};
 
 #[derive(Debug, Parser)]
 pub enum Command {
@@ -8,8 +8,9 @@ pub enum Command {
 
 #[derive(Debug, Parser)]
 #[clap(
-    version = crate_version!(),
-    author = crate_authors!(", "),
+    about,
+    version,
+    author,
     global_setting = AppSettings::InferSubcommands,
     global_setting = AppSettings::PropagateVersion,
 )]