Assignment Management

There is an error in file format validation when student uploading assignment when you try to upload file with multiple dots. 
e.g: file name = "school.assignment.docx"
It throws error format miss match even the format is set same.
Fixed the error using below code:

@api.constrains("submit_assign", "file_name")
def check_file_format(self):
    if self.file_name:
        file_format = '.'+ self.file_name.split(".")[-1]
        if file_format != self.attachfile_format:
            raise ValidationError(_(
                """Kindly attach file with format: %s!""") % self.attachfile_format)