editors/sly-asdf: Update to the latest version (0.2.0 + 1 one commit)

As the port seems to be using explicit versioning, switch to a "version-date"
scheme and bump PORTEPOCH.

Changes: A fix for query-replace across a system, a possible ECL fix, fix
jumping to source for errors.

Changelog: https://github.com/mmgeorge/sly-asdf/compare/bcaeba9b...6f9d7514

PR: 271654

(cherry picked from commit 2bc331659d6921f8ac6ebad1429b02d987021494)