ci: Pin json below 3 when testing against Faraday 1 (#146)

Faraday 1's JSON response middleware passes its options to JSON.parse as a positional hash, which json 3.0 removed, so every Faraday 1 cell fails in spec/json_spec.rb since json 3.0.2 became the default resolution.

Author: georgeguimaraes

Gemfile

@@ -6,12 +6,18 @@ install_if -> { ENV['FARADAY_VERSION'] } do
   gem 'faraday', ENV['FARADAY_VERSION']
 end
 
-if /\D*([\d.]*)/.match(ENV.fetch('FARADAY_VERSION', ''))[1].start_with?('0')
+faraday_version = /\D*([\d.]*)/.match(ENV.fetch('FARADAY_VERSION', ''))[1]
+
+if faraday_version.start_with?('0')
   gem 'faraday_middleware'
 elsif ENV['FARADAY_ADAPTER'] == 'em_http'
   gem 'faraday-em_http'
 end
 
+# Faraday 1's JSON response middleware passes its options to JSON.parse as a
+# positional hash, which json 3 no longer accepts.
+gem 'json', '< 3' if faraday_version.start_with?('1')
+
 gem 'activesupport',      '>= 7.0'
 gem 'em-http-request',    '>= 1.1'
 gem 'rackup'