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/register.go

@@ -274,7 +274,9 @@ func doRegister(cfg *config.Config, inputs *registerInputs) error {
 	cli := client.New(
 		inputs.InstanceAddr,
 		inputs.Insecure,
-		"", "",
+		"",
+		"",
+		version,
 	)
 
 	for {