more CI debugging

Looks like the .rspec file is not being loaded in CI when we run
`bundle exec rake spec`.  Trying `bundle exec rspec` instead.

Author: David M. Lary

.github/workflows/main.yml

@@ -31,4 +31,4 @@ jobs:
           ruby-version: "${{ matrix.ruby }}"
           bundler-cache: true
       - run: bundle install
-      - run: bundle exec rake spec
+      - run: bundle exec rspec