Test on and support multiple versions of Rack

With this change, Rack::Session::Redic now supports and tests against
both Rack v2 and v3 transparently.

.github/workflows/main.yml

@@ -23,11 +23,17 @@ jobs:
         ports:
           - 6379:6379
 
-    name: Test (${{ matrix.ruby }} / ${{ matrix.os }})
     strategy:
+      fail-fast: false
       matrix:
         ruby: ${{ fromJson(needs.ruby-versions.outputs.versions) }}
         os: [ubuntu-latest]
+        rack: [2, 3]
+
+    name: "Test Ruby: ${{ matrix.ruby }} Rack: ${{ matrix.rack }} OS: ${{ matrix.os }}"
+
+    env:
+      BUNDLE_GEMFILE: ${{ github.workspace }}/gemfiles/rack${{ matrix.rack }}.gemfile
 
     runs-on: ${{ matrix.os }}
     steps:

README.md

@@ -40,12 +40,6 @@ Or install it yourself as:
 gem install rack-redic
 ```
 
-### Rack 3
-
-With the release of Rack v3.0.0 Rack's `Session` module has been extracted into
-its own gem. To use `Rack::Session::Redic` with Rack v3 be sure to add `gem
-'rack-session'` to your `Gemfile` as well.
-
 ## Usage
 
 Anywhere in your Rack application just add:

gemfiles/rack2.gemfile

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+source 'https://rubygems.org'
+
+gemspec(path: '../')
+
+gem 'minitest', '~> 5'
+gem 'rack', '~> 2'
+gem 'rake', '~> 13'
+gem 'rubocop', '~> 1'
+gem 'rubocop-minitest'
+gem 'rubocop-packaging'
+gem 'rubocop-performance', '~> 1'
+gem 'rubocop-rake'

gemfiles/rack3.gemfile

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+source 'https://rubygems.org'
+
+gemspec(path: '../')
+
+gem 'minitest', '~> 5'
+gem 'rack', '~> 3'
+gem 'rake', '~> 13'
+gem 'rubocop', '~> 1'
+gem 'rubocop-minitest'
+gem 'rubocop-packaging'
+gem 'rubocop-performance', '~> 1'
+gem 'rubocop-rake'

rack-redic.gemspec

@@ -12,7 +12,8 @@ Gem::Specification.new do |spec|
   spec.files = Dir['lib/**/*', 'README.md', 'LICENSE.txt']
   spec.required_ruby_version = '>= 2.5.0'
 
-  spec.add_runtime_dependency 'rack', '~> 2'
+  spec.add_runtime_dependency 'rack', '>= 2.0.0', '< 4'
+  spec.add_runtime_dependency 'rack-session'
   spec.add_runtime_dependency 'redic', '~> 1'
 
   spec.metadata['bug_tracker_uri'] = "#{ spec.homepage }/issues"