feat(cli): add version flag to CLI (#49)

`actionbase --version` now prints the CLI version.

Author: zipdoki

cli/cmd/actionbase/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"os"
 
 	"github.com/kakao/actionbase/internal/runner"
@@ -21,6 +22,11 @@ const (
 func main() {
 	parser := util.ParseArgs(os.Args)
 
+	if _, found := parser.GetLenient("version"); found {
+		fmt.Println("v" + Version)
+		return
+	}
+
 	host, found := parser.Get(hostParamKey)
 	if !found {
 		host = DefaultHost