Allow compressed osm.bz2 file

Line 121 in f0702ac

if f.endswith('.pbf'):

For getting DAILY updated full planet.osm, AFAIK only osm.bz2 are available, see:
https://wiki.openstreetmap.org/wiki/Planet.osm#Planet.osm_mirrors
For instance: https://ftp5.gwdg.de/pub/misc/openstreetmap/planet.openstreetmap.org/planet/planet-latest.osm.bz2
It would be great to be able to use this, as imposm supports bz2

I need to check why only PBF is allowed. But if I remember correctly, it was because of the timestamp. In the PBF, the timestamp is usually included.

https://github.com/kartoza/docker-osm/blob/develop/docker-osmupdate/download.py#L111

This line will take the timestamp from the PBF file and I'm not sure it works well with an XML BZ2 file.

In the first release, I was using the timestamp.txt which is sometimes included : http://download.openstreetmap.fr/extracts/ next to the PBF file to get the timestamp and then I realize that it was also working without.