Merge pull request #173 from a-zagaevskiy/master

fix handles leakage

Windows API docs states that process handlers should be released:

> When you are finished with the handle, be sure to close it using the [CloseHandle](https://docs.microsoft.com/en-us/windows/win32/api/handleapi/nf-handleapi-closehandle) function.

https://docs.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-openprocess

process_windows.go

@@ -19,6 +19,7 @@ func _pidAlive(pid int) bool {
 	if err != nil {
 		return false
 	}
+	defer syscall.CloseHandle(h)
 
 	var ec uint32
 	if e := syscall.GetExitCodeProcess(h, &ec); e != nil {