community/libcouchbase: upgrade to 3.1.0

• https://github.com/couchbase/libcouchbase/releases
• https://pecl.php.net/package-changelog.php?package=couchbase&release=3.1.0

perl-couchbase has no compatible release yet https://github.com/mnunberg/perl-Couchbase-Client/issues/51 suggestion to move to unmaintained !18998 (merged)