Specified git branch for google benchmark fetch in benchmark test

Update documentation

The default branch was renamed from "master" to "main", which breaks the cloning process.

Possibility to use without the dependency to file io and streams to use in intel sgx enclaves

Consistency with `using` in README.md

Add C++ standards to macOS matrix

Keep consistent formatting

Fix CI

Update URLs to HTTPS

Link to Conan Center package added