If the current ERFA leap second table is out of date, try to update it.

Uses astropy.utils.iers.LeapSeconds.auto_open to try to find an up-to-date table. See that routine for the definition of “out of date”.

In order to make it safe to call this any time, all exceptions are turned into warnings,

files : list of path, optional

List of files/URLs to attempt to open. By default, uses defined by astropy.utils.iers.LeapSeconds.auto_open, which includes the table used by ERFA itself, so if that is up to date, nothing will happen.

n_update : int

Number of items updated.