Upgrade faraday dependency

[ljachymczyk]

Faraday gem version used in this project is quite old (from early 2019). It might be nice to upgrade it so that projects using format_parser are allowed to benefit from new features of latest faraday version.

Checked rspec, it does not seem to break anything. Also tested manually and it seem to work for me.

[fabioperrella]

Thank you @ljachymczyk for your contribution!

[fabioperrella]

I see that the tests are failing for old Rubies.

What about dropping support for EOL Rubies?

# format_parser.gemspec
spec.required_ruby_version = Gem::Requirement.new(">= 2.6.0")

Also changing the matrix on format_parser.gemspec