devel/py-subversion: split test target, with fix tests in python >= 3.14

To fix both of latest and LTS, add a patch to fix the tests
both in devel/subversion and devel/subversion-lts.

PR: 294183
MFH: 2026Q3
(cherry picked from commit b8e6b2a99628582839f56de7301796fba0aa0326)