Support PostgreSQL 12
Description
The primary change: add support of Postgres 12.
Additionally:
- use Ubuntu 18.04 instead of 16.04
- cleanup Dockerfile
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the MR description has been reviewed 
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this MR contains text changes and they have been reviewed OR there are no texts changes 
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this MR contains GUI/CLI changes and they have been reviewed OR there are no GUI/CLI changes 
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this MR contains API changes and they have been reviewed OR there are no API changes 
Related issue
Examples
Edited  by Nikolay Samokhvalov