ReleaseOnGithub is not async safe

[norberturkiewicz]

Asset upload needs to wait on result of upload.

Let upload start in thread and wait for result with .Result

     _←{
         f←File.OpenRead⊂⍵
         au←⎕NEW ReleaseAssetUpload
         au.FileName←∊1↓⎕NPARTS ⍵
         au.ContentType←gct ⍵
         au.RawData←f
         resultUpload←c.Repository.Release.UploadAsset(release au)
         _←⎕DL 1
         _←resultUpload.Result
         0
     }¨u