Remove OpenSSL from the dependency tree on all platforms

[romac]

Summary of Bug

OpenSSL released a security advisory on November 1st which contains two CVE with severity HIGH.

While Hermes is mostly using the Rustls TLS implementation which is not affected, we should ensure that we do not depend on OpenSSL at all to avoid opening up the door for such vulnerabilities in the future.

At the moment, only the ibc-chain-registry transitively depends on OpenSSL on Linux via the reqwest crate which is used to fetch data from the chain registry on GitHub.

Version

master

Steps to Reproduce

Either on Linux or with the x86_64-unknown-linux-gnu toolchain installed:

$ git clone https://github.com/informalsystems/hermes
$ cd hermes
$ cargo tree --target x86_64-unknown-linux-gnu -i openssl-sys
openssl-sys v0.9.77
├── native-tls v0.2.10
│   ├── hyper-tls v0.5.0
│   │   └── reqwest v0.11.12
│   │       └── ibc-chain-registry v0.1.0 (/hermes/crates/ibc-chain-registry)
│   │           └── ibc-relayer-cli v1.1.0 (/hermes/crates/relayer-cli)
│   │               ├── check-guide v0.1.0 (/hermes/tools/check-guide)
│   │               ├── ibc-integration-test v0.20.0 (/hermes/tools/integration-test)
│   │               └── ibc-test-framework v0.20.0 (/hermes/tools/test-framework)
│   │                   └── ibc-integration-test v0.20.0 (/hermes/tools/integration-test)
│   ├── reqwest v0.11.12 (*)
│   └── tokio-native-tls v0.3.0
│       ├── hyper-tls v0.5.0 (*)
│       └── reqwest v0.11.12 (*)
└── openssl v0.10.42
    └── native-tls v0.2.10 (*)

Acceptance Criteria

The commands above do not mention openssl, openssl-sys nor native-tls.

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