Migrate to GitHub Actions for tests workflow (#79)

* Add Tests GHA workflow to replace Travis

* Delete .travis.yml

* Fix warning on regex ambiguity, wrap in parens

Simple fix for this ambiguity warning to wrap the arguments with parens. This warning was reported on all versions of Ruby tested in this update.

```
clockwork/test/clockwork_test.rb:43: warning: ambiguity between regexp and two divisions: wrap regexp in parentheses or add a space after `/' operator
clockwork/test/clockwork_test.rb:57: warning: ambiguity between regexp and two divisions: wrap regexp in parentheses or add a space after `/' operator
```

* Remove gemfiles folder

These are no longer needed since we dynamically change the ActiveSupport version installed through an environment variable in the root Gemfile.

.github/workflows/tests.yml

@@ -0,0 +1,36 @@
+name: Tests
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        ruby: [ "2.7", "3.0", "3.1", "3.2", jruby ]
+        active_support: [ "6.0", "7.0" ]
+        exclude:
+          - ruby: "3.0"
+            active_support: "6.0"
+          - ruby: "3.1"
+            active_support: "6.0"
+          - ruby: "3.2"
+            active_support: "6.0"
+    name: Ruby ${{ matrix.ruby }} - ActiveSupport ${{ matrix.active_support }}
+    env:
+      ACTIVE_SUPPORT_VERSION: ${{ matrix.active_support }}
+    steps:
+      - uses: actions/checkout@v3
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+      - name: Run Tests
+        env:
+          RUBYOPT: "-W:deprecated" # Show Ruby's deprecation warnings
+        run: |
+          bundle exec rake

Gemfile

@@ -1,3 +1,8 @@
 source 'https://rubygems.org'
 
 gemspec
+
+rails_version = ENV.fetch("ACTIVE_SUPPORT_VERSION", "7.0")
+
+gem "activesupport", "~> #{rails_version}"
+gem "minitest", "~> 5.0"

test/clockwork_test.rb

@@ -40,7 +40,7 @@
     Clockwork.run
     assert run
     assert @log_output.string.include?("Triggering 'an event'")
-    assert_match /Finished 'an event' duration_ms=\d+ error=nil/, @log_output.string
+    assert_match(/Finished 'an event' duration_ms=\d+ error=nil/, @log_output.string)
   end
 
   it 'should log exceptions' do
@@ -54,7 +54,7 @@
     Clockwork.run
     assert run
     assert @log_output.string.include?("Triggering 'an event'")
-    assert_match /Finished 'an event' duration_ms=\d+ error=#<RuntimeError: boom>/, @log_output.string
+    assert_match(/Finished 'an event' duration_ms=\d+ error=#<RuntimeError: boom>/, @log_output.string)
   end
 
   it 'should pass event without modification to handler' do