timestamp comparison in client expiration logic

[rnbguy]

The following inequality should be >=

https://github.com/cosmos/ibc-rs/blob/2378cd4ba45094b8ed856ff7dba5f1d0882f59ae/ibc-clients/ics07-tendermint/src/client_state/validation.rs#L224-L225

Considering the is_within_trust_period logic from tendermint-rs.

To summarize, tendermint-rs expires a header at trusted_header_time + trusting_period. However, in ibc-rs, a header is active till trusted_header_time + trusting_period.