Fix IPv6 error caused by TLS configuration

[ljoss17]

Version

Hermes v1.10.3

Summary

When configuring TLS with IPv6 gRPC endpoint, https://github.com/informalsystems/hermes/blob/v1.10.3/crates/relayer/src/util.rs#L26, a transport error: InvalidDnsNameError will be thrown since the characters [ and ] are not parsed by rustls https://docs.rs/rustls-pki-types/1.10.0/src/rustls_pki_types/server_name.rs.html#326.

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