faraday specs compatible with faraday 2 require ruby >= 2.6

- drop ruby 2.2, 2.5
- add ruby 2.6
- bump jruby to 9.3 for ruby 2.6 compatibility

Author: barmintor

.github/workflows/ci.yml

@@ -9,14 +9,12 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby-version: ['2.5.8', '2.7.6', 'jruby-9.2.20.1']
+        ruby-version: ['2.6.9', '2.7.6', 'jruby-9.3.0.0']
         gemfile:
           - rails_52
           - rails_60
           - rails_61
         include:
-          - ruby-version: 2.2.10
-            gemfile: rails_52
           - ruby-version: 2.7.6
             gemfile: rails_70
         exclude:

ruby-oai.gemspec

@@ -13,7 +13,6 @@ Gem::Specification.new do |s|
 
     s.add_dependency('builder', '>=3.1.0')
     s.add_dependency('faraday', "< 3")
-    #s.add_dependency('faraday_middleware')
     s.add_dependency("faraday-follow_redirects", ">= 0.3.0", "< 2")