Can't upgrade due to old docker version

[itsbhanusharma (Bhanu Sharma)]

1. What is Your docker version?
2. Did You try solutions suggested in this FAQ?

PostgreSQL 12 update

WARNING! If your database is very large, you will need a lot of extra disk space (2x database size) and should be very careful with this upgrade! We just landed the long waited PostgreSQL major version upgrade. Any site admins rebuilding Discourse from the command line will be upgraded to PostgreSQL 12 from the old PostgreSQL 10. We are running this new version for a while on Meta, and everything is working fine. PostgreSQL 12 brings lots of improvements that will be automatical…