Inject version when building and report version to Gitea via log and header (#43)

close #42
1. Inject runner version when `make build`
After building, executing command line: `./act_runner -v` or `./act_runner --version`, the version of runner is printed.
![image](/attachments/e25efbd3-79b3-49a5-b93f-42646d42c707)

2. In `Actions` UI:
![image](/attachments/36c57470-2a1d-4796-9eb0-de3988ab88e1)

3. Set request header in http client interceptor.

Co-authored-by: sillyguodong <gedong_1994@163.com>
Reviewed-on: https://gitea.com/gitea/act_runner/pulls/43
Reviewed-by: delvh <dev.lh@web.de>
Reviewed-by: Jason Song <i@wolfogre.com>
Co-authored-by: sillyguodong <sillyguodong@noreply.gitea.io>
Co-committed-by: sillyguodong <sillyguodong@noreply.gitea.io>

cmd/cmd.go

@@ -10,7 +10,8 @@ import (
 	"github.com/spf13/cobra"
 )
 
-const version = "0.1.5"
+// the version of act_runner
+var version = "develop"
 
 type globalArgs struct {
 	EnvFile string
@@ -23,7 +24,7 @@ func Execute(ctx context.Context) {
 
 	// ./act_runner
 	rootCmd := &cobra.Command{
-		Use:          "act [event name to run]\nIf no event name passed, will default to \"on: push\"",
+		Use:          "act_runner [event name to run]\nIf no event name passed, will default to \"on: push\"",
 		Short:        "Run GitHub actions locally by specifying the event name (e.g. `push`) or an action name directly.",
 		Args:         cobra.MaximumNArgs(1),
 		Version:      version,