asyncpg v0.20.0

Improvements

• Support Python 3.8
  (by @1st1 in #504)

• Support PgBouncer by sending only a single SYNC message per query
  (by @fvannee in b043fbd)

Bug Fixes

• Handle IP values with prefix in "inet" type as ipaddress.IPvXInterface
  (by @elprans in 5a4daf7 for #497)

• Close transport if connection times out
  (by @hexrain in 926f483 for #468)

• Use faster UUID codecs; make UUID decoding/encoding/operations 2-7x faster
  (by @1st1 in edde3ff)

• Use loop.start_tls() to upgrade connections to SSL
  (by @1st1 in bdba7ce)

Build

• Bump Cython to 0.29.14
  (by @1st1 in 7cb31bc)