Upgrade PostgreSQL

[jpmckinney]

Version 12 (2019-10-03) has some nice new features (SQL/JSON path expressions for querying, generated columns for Kingfisher Summarize) as well as performance improvements. https://www.postgresql.org/about/news/1976/

[jpmckinney]

https://www.postgresql.org/about/news/postgresql-13-released-2077/ (2020-09-24) now released.

[jpmckinney]

https://www.postgresql.org/about/news/postgresql-14-released-2318/ I haven't read release notes yet.

[jpmckinney]

Reading all migration notes now:

• https://www.postgresql.org/docs/12/release-12.html#id-1.11.6.20.4

  Move recovery.conf settings into postgresql.conf

  Updated our documentation. pgbackrest already does the right thing for 12+.

• https://www.postgresql.org/docs/13/release-13.html#id-1.11.6.16.4

  Change the way non-default effective_io_concurrency values affect concurrency

  I opened Does effective_io_concurrency need to be set differently for PostgreSQL 13+? le0pard/pgtune#79 to clarify.

  Rename configuration parameter wal_keep_segments to wal_keep_size

  Applied the provided formula wal_keep_size = wal_keep_segments * wal_segment_size to get 320 = 20 * 16

• https://www.postgresql.org/docs/14/release-14.html#id-1.11.6.13.4

  No relevant changes.

• https://www.postgresql.org/docs/15/release-15.html#id-1.11.6.8.4

  Remove PUBLIC creation permission on the public schema

  We already do this. The registry is on 12 and redash is on 13. When all servers are at least 15, we can remove the code as it will be unnecessary.

[jpmckinney]

I did the docs in fd2bdd0 and upgrade/changes in 1951287 in this PR #418. Merging into #402.