fix: Add openssl and rustls feature flags in ethers-middleware

[oblique]

Motivation

I was working on a project with requirement to use OpenSSL, so I added this:

ethers = { version = "1.0.2", default-features = false, features = ["ws", "openssl"] }

But I noticed that rustls was still building.

Solution

The problem was that ethers-middleware was explicitly using reqwest with rustls-tls enabled, so I added rustls and openssl feature flags to it.

PR Checklist

• Added Tests
• Added Documentation
• Updated the changelog
• Breaking changes

[mattsse]

lgtm