shells/fish: Update to 3.6.1
While here do some minor housekeeping;
- Remove superfluous post-stage-MANPAGES-off target, cleanup is already handled with PLIST substitutions.
- Collapse the PORT_OPTIONS conditional pre-checks back into DOCS. We only need sphinx when building the documentation, not MANPAGES, as such disallow multiple jobs if DOCS is enabled.
Changes: https://github.com/fish-shell/fish-shell/releases/3.6.1
PR: 271558
Approved by: asomers (maintainer)