emulators/rpcs3: update to 0.0.20

Temporarily drop commit count from package version as this matches
actual tag but kept verbose for --version or ~/.cache/rpcs3/RPCS3.log

Changes: https://github.com/RPCS3/rpcs3/compare/cb2748ae0...61d985263
(cherry picked from commit 46e4c577ee6844fe353c3c52fcb612f9b3f0d2f5)