Show warning of unsupported DB for Postgres 11 in Plan your upgrade

Issue Summary

Bitbucket 7.13 is supporting Postgres 9.6 ~ 12 as described in Bitbuckrt Supported platforms

However, it shows a warning of unsupported DB in Plan your upgrade when customer is using Postgres 11.

Steps to Reproduce

1. Install bitbucket 7.13.0
2. Connecting to PostgresSQL 11.11
3. Login bitbucket and move to 'Plan your upgrade'

Expected Results

No warning

Actual Results

There is a warning:

Your current database version won't be supported.

Workaround

Currently there is no known workaround for this behavior.