Add clustering algorithms (postgresml#795)

Also publish extension

Add publish to dockerhub

v2.6.0 (postgresml#762)

Release 2.5.3 (postgresml#734)

Allow installation without superuser (postgresml#712)

Update sql interface for 2.5.0 (postgresml#696)

update version (postgresml#695)

release 2.4.7