Incorrectly formatted "logging.info" statement causes a hang in cf.Field.collapse

At 3.9.0, some rogue commas can cause a hang to occur

# cf/field.py
            logger.info(
                "  After collapse of data:\n"
                f"    f.shape = {f.shape}\n"
                f"    f.dtype = {f.dtype}\n",
                f"collapse_axes = {collapse_axes}",
            )  # pragma: no cover

https://github.com/NCAS-CMS/cf-python/blob/v3.9.0/cf/field.py#L9894-L9899

All of the commas in this snippet should be removed.