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 <[email protected]>
Reviewed-on: https://gitea.com/gitea/act_runner/pulls/43
Reviewed-by: delvh <[email protected]>
Reviewed-by: Jason Song <[email protected]>
Co-authored-by: sillyguodong <[email protected]>
Co-committed-by: sillyguodong <[email protected]>

core/runner.go

@@ -4,8 +4,9 @@
 package core
 
 const (
-	UUIDHeader  = "x-runner-uuid"
-	TokenHeader = "x-runner-token"
+	UUIDHeader    = "x-runner-uuid"
+	TokenHeader   = "x-runner-token"
+	VersionHeader = "x-runner-version"
 )
 
 // Runner struct