deprecate BuildRoot.uploadDir method

Fixes: https://pagure.io/koji/issue/839

builder/kojid

@@ -525,6 +525,7 @@ class BuildRoot(object):
         append '.' + suffix to the filenames, so that successive uploads
         of the same directory won't overwrite each other, if the files have
         the same name but different contents."""
+        koji.util.deprecated('BuildRoot.uploadDir method is deprecated and will be removed in 1.19')
         if not os.path.isdir(dirpath):
             return
         uploadpath = self.getUploadPath()