Add pgRouting version to to output

[rustprooflabs]

Details

The processing output currently lists a few other important versions. Would be helpful to include pgRouting, especially after being surprised in #408.

2025-12-20 09:33:59,571:INFO:pgosm-flex:helpers:2025-12-20 09:33:59  osm2pgsql version 2.2.0
2025-12-20 09:33:59,576:INFO:pgosm-flex:helpers:2025-12-20 09:33:59  Database version: 18.1 (Debian 18.1-1.pgdg13+2)
2025-12-20 09:33:59,576:INFO:pgosm-flex:helpers:2025-12-20 09:33:59  PostGIS version: 3.6

[rustprooflabs]

Oh, that logging comes from osm2pgsql, not something internal where I can simply tack a new function call on for pgr_version(). If this is added it wouldn't be able to be right along with the other 3 versions I was looking at. Might close this one.

If detecting breakages on the pgRouting functions is important I think the right path is to add new tests to run by make to verify functionality.

---

Same basic output as the description, just with the important preceeding line showing at this point it's starting osm2pgsql, not logging this in custom code.

2025-12-29 17:14:03,600:INFO:pgosm-flex:pgosm_flex:Running osm2pgsql
2025-12-29 17:14:03,608:INFO:pgosm-flex:helpers:2025-12-29 17:14:03  osm2pgsql version 2.2.0
2025-12-29 17:14:03,612:INFO:pgosm-flex:helpers:2025-12-29 17:14:03  Database version: 18.1 (Debian 18.1-1.pgdg13+2)
2025-12-29 17:14:03,612:INFO:pgosm-flex:helpers:2025-12-29 17:14:03  PostGIS version: 3.6