[pgAdmin4][Patch]: RM_ 2582 - Backup : Fix compression value

[Surinder Kumar]

Hi

*Issue:*
In Backup, compression field can only accept values between 0 to 9. But if
the field is clicked, an empty value is set into the model, So, added a
check to remove the model attribute if the field is an empty string before
data is sent to the server.

Please find attached patch.

Thanks,
Surinder

RM_2582.patch
Description: Binary data