I don’t know exactly what is going on but postgrex seems to be failing parsing a version, I expect the database’s…
You’re on PostgreSQL 11.7 which is from Feb 2020, but your postgrex is very old: v0.12.2 was released in Sep 2016.
Try updating your postgrex library version, the latest is v0.15.3.
mix deps.unlock postgrex
mix deps.update postgrex
And/or change the version requirement in your mix.exs file
