Remove boto 'set_acl' call after upload (#49)

Since it causes access denied errors when the IAM user does not have
`PutObjectAcl` permissions for the S3 bucket, preventing the use of a
more locked down IAM user for deployment.

It seems preferable to leave the bucket ACLs to the bucket owner,
and for `bob deploy` to only upload the file.

Closes W-8134681.

bob/models.py

@@ -192,6 +192,5 @@ class Formula(object):
 
         # Upload the archive, set permissions.
         key.set_contents_from_filename(self.archived_path)
-        key.set_acl('public-read')
 
         print_stderr('Upload complete!')