Fix typo in test identifiers for the `is/2` Prolog standard predicate
Fix typo in test identifiers for the `is/2` Prolog standard predicate

LogtalkDotOrg/logtalk3,LogtalkDotOrg/logtalk3,LogtalkDotOrg/logtalk3,LogtalkDotOrg/logtalk3,LogtalkDotOrg/logtalk3,LogtalkDotOrg/logtalk3,LogtalkDotOrg/logtalk3