Changing groupName for GroupName in delete_placement_group

[joaomarceloalencar]

When I try using delete_placement_group I get an error:

julia> Ec2.delete_placement_group("test")
ERROR: AWS.AWSExceptions.AWSException: UnknownParameter -- The parameter groupName is not recognized
HTTP.Exceptions.StatusError(400, "POST", "/", HTTP.Messages.Response:

I changed in ec2.jl for 'GroupName' and it worked.