Use rake task to run specs in CI

Ensures to run all specs, including the isolated ones

Author: fnordfish

.github/workflows/main.yml

@@ -28,7 +28,7 @@ jobs:
         ruby-version: ${{ matrix.ruby }}
         bundler-cache: true
     - name: RSpec tests
-      run: bundle exec rspec
+      run: bundle exec rake spec
 
   lint:
     runs-on: ubuntu-latest