accessibility/at-spi2-core: update to 2.48.0

What's new in at-spi2-core 2.48.0:

• Add a "atk-only" build option. This allows atk to be built without libdbus installed, but it does not build libatspi or the atk bridge.
• Fix some typos in the documentation.

The atk-only support was added upstraem by Corey Halpin

Reported by: Dmitry Pryakhin <graahnul.grom@ya.ru>
PR: 269996
Exp-run by: antoine