testing/srb2: upgrade to 2.2.15
- https://git.do.srb2.org/STJr/SRB2/-/wikis/Changelogs/2.2.14
- https://git.do.srb2.org/STJr/SRB2/-/wikis/Changelogs/2.2.15
fix-backtrace.patch is no longer needed as of https://git.do.srb2.org/STJr/SRB2/-/commit/13cfc5ef597f994b9100a21a1f0b2c6acca8fe75
Resource file changes are outlined in the changelog for 2.2.14.
Edited by Jordan Christiansen