ports-mgmt/synth: update to 3.08 release (+)

What's new since 3.03:

3.04 (fix flavored package cleanup)
3.05 (fix flavored package cleanup, part 2)
3.06 (fix flavored package cleanup, part 3)
3.07 (Drop obsolete flavors during repo build)
3.08 (Increment package limit from 40K to 80K)

MFH: 2025Q1
(cherry picked from commit a86780d11ae14a7a126a140899d754856731189c)