Change shorthand for -verbose from -v to -V

-v clashes with the shorthand for printing the app version with
urlfave/cli. This wasn't noticed in debug/ci because urlfave/cli
only defines the --version/-v flag when the app version is non empty
and we only fill it in for release builds. Thanks to @danarrib for
the heads up.

Author: fiam

main.go

@@ -72,7 +72,7 @@ func main() {
 		},
 		&cli.BoolFlag{
 			Name:        "verbose",
-			Aliases:     []string{"v"},
+			Aliases:     []string{"V"},
 			Usage:       "Enable verbose output",
 			Destination: &verboseFlag,
 		},