Reduce Slashing Penalty for Downtime from 1% to 0.3%

This proposal aims to adjust the slashing parameters to encourage validator participation and reduce the punishment for downtime. Specifically, the `slash_fraction_downtime` parameter will be lowered from 0.01 (1%) to 0.003 (0.3%). This change helps balance security and validator sustainability, reducing the risk of severe penalties for temporary outages while maintaining deterrence against prolonged downtime.