Consider making `cp_reconnect` true by default

[anoadragon453]

A somewhat recent change in Synapse enabled by default the behaviour of reconnecting to the Postgres database after losing connection automatically.

We likely want to consider doing the same for Sygnal.

sygnal/sygnal/sygnal.py

Lines 150 to 155 in e1b9eb8

	if db_name == "psycopg2":
	logger.info("Using postgresql database")
	self.database_engine = "postgresql"
	self.database = ConnectionPool(
	"psycopg2", cp_reactor=self.reactor, **config["database"].get("args")
	)