snowflake: update to 2.4.2

snowflake: update to 2.4.2

Changes in version v2.4.2 - 2023-01-13
- Issue 40208: Enhance help info for capacity flag
- Issue 40232: Update README and fix help output
- Issue 40173: Increase clientIDAddrMapCapacity
- Issue 40177: Manually unlock mutex in ClientMap.SendQueue
- Issue 40177: Have SnowflakeClientConn implement io.WriterTo
- Issue 40179: Reduce turbotunnel queueSize from 2048 to 512
- Issue 40187/40199: Take ownership of buffer in QueuePacketConn QueueIncoming/WriteTo
- Add more tests for URL encoded IPs (safelog)
- Fix server flag name
- Issue 40200: Use multiple parallel KCP state machines in the server
- Add a num-turbotunnel server transport option
- Issue: 40241: Switch default proxy STUN server to stun.l.google.com

Signed-off-by: Nick Hainke <vincent@systemli.org>
(cherry picked from commit 5435ddb8f8f626997202b96d0cc1306c2da03a75)