asyncpg v0.19.0

Improvements

• Add support for SCRAM-SHA-256 authentication.
  (by @jkatz in 2d76f50)

• Add PostgreSQL 12 support
  (by @elprans in 2326153)

Bug Fixes

• Remove preexec_fn hack from test cluster management
  (by @elprans in 36ed11d)

• Fix DeprecationWarning in the docstring of copy_from_query()
  (by @elprans in 482a39a)

• Allow specifying the target version when generating the release log
  (by @elprans in 43a7b21)

• Check for .flake8 after importing flake8
  (by @dotlambda in aaeb707)

• Include .flake8 in PyPI tarball
  (by @dotlambda in 43c6b9c)

• fix timezone type label in docs
  (by @claws in e91e491)

• Fix _StatementCache.clear() PS memory leak
  (by @un-def in f4aa9bf for #416)

• fix for warning_callback not yet defined
  (by @samuelcolvin in 354d9be)

• Fix assertion fail on copy_records_to_table
  (by Petr Reznikov in ae5a89d)

• Do not look for a port in a Unix socket domain path
  (by @Lawouach in b773912 for #419)

• Unquote connection string components properly
  (by @elprans in 5513b9d for #418)

• Remove superfluous transaction from a cursor example
  (by @elprans in 32fccaa for #475)