imap: increase connection-timeout to 90 seconds

In case when the server does not support IDLE command, then default
value of the polling interval set in go-imap to 60 seconds is larger
then the default value of connection-timeout set to 30 seconds.
Therefore aerc disconnects while polling every 30 seconds, because there
is no activity.

This was tested on seznam.cz as well as a self hosted dovecot, where the
IDLE command was removed from announced capabilities.

Changelog-fixed: IMAP servers without IDLE support do not timeout
 while polling.
Changelog-changed: The default IMAP connection timeout has been
 increased to 90 seconds.
Signed-off-by: Jakub Růžička <[email protected]>
Tested-by: Karel Balej <[email protected]>
Acked-by: Robin Jarry <[email protected]>

doc/aerc-imap.5.scd

@@ -74,7 +74,7 @@ are available:
 	Maximum delay to establish a connection to the IMAP server. See
 	https://pkg.go.dev/time#ParseDuration.
 
-	Default: _30s_
+	Default: _90s_
 
 *keepalive-period* = _<duration>_
 	The interval between the last data packet sent (simple ACKs are not

worker/imap/configure.go

@@ -72,7 +72,7 @@ func (w *IMAPWorker) handleConfigure(msg *types.Configure) error {
 	w.config.idle_timeout = 10 * time.Second
 	w.config.idle_debounce = 10 * time.Millisecond
 
-	w.config.connection_timeout = 30 * time.Second
+	w.config.connection_timeout = 90 * time.Second
 	w.config.keepalive_period = 0 * time.Second
 	w.config.keepalive_probes = 3
 	w.config.keepalive_interval = 3