archivers/lzma: update to 26.02
- add 7-zip.org to MASTER_SITES as distfile not yet on Sourceforge (but will probably be uploaded soon)
Upstream changes:
- Some bugs and vulnerabilities were fixed.
MFH: 2026Q2
(cherry picked from commit 2821c2b2c26f4fa71ad6a1913aca848c4caafd66)