Setting user language to something other than English affects API responses, including error messages

[rafauke]

Describe the bug
Using language other than English in Gitlab user preferences changes API requests. This breaks some functionalities since some errors are recognized by regexp patterns. Things like:

    # glcli.py:117
    except gitlab.GitlabHttpError as exception:

        if (
            exception.args[0]
            and "key" in exception.args[0]
            and "has already been taken" in str(exception.args[0]["key"])
        ):
            return set_project_var(scope, value, token, variable_name, update=True)

        logging.info(exception)                 
        error = f"Gitlab: {exception.args[0][4:]}"
        http_codes = {
            "403": f"Access denied to project {group}/{project}. Check your permissions.",
            "404": f"Project {group}/{project} does not exist.",
        }

Won't catch an exception like this:

400: {'key': ['(VAULT_TOKEN) zostało już zajęte']}