Use British English spelling in tag name for birthing_center

[Hufkratzer]

A while ago it was discussed on the tagging mailing list that the tag name for birthing centres should better be birthing_centre (en-GB) than (currently) birthing_center (en-US), like in sports centres and so on.

OpenStreetBrowser already supports the corrected spelling (example), the maintainers of "babykarte" have assured that they will support it (babykarte/babykarte#65).

So please change that in https://github.com/openstreetmap/id-tagging-schema/blob/main/data/presets/healthcare/birthing_center.json and also please add it in https://github.com/openstreetmap/id-tagging-schema/blob/main/data/deprecated.json.

For JOSM there are just some user defined additional healthcare presets which contain this tag. I will try to notify the maintainer(s) after you have changed the spelling in iD.