Add cache for rspec persistence file

.github/workflows/test-ruby.yml

@@ -137,6 +137,18 @@ jobs:
           bin/rails db:setup
           bin/flatware fan bin/rails db:test:prepare
 
+      - name: Cache RSpec persistence file
+        uses: actions/cache@v4
+        with:
+          path: |
+            tmp/rspec/examples.txt
+          key: rspec-persistence-${{ github.head_ref || github.ref_name }}-${{ github.sha }}
+          restore-keys: |
+            rspec-persistence-${{ github.head_ref || github.ref_name }}-${{ github.sha }}
+            rspec-persistence-${{ github.head_ref || github.ref_name }}
+            rspec-persistence-main
+            rspec-persistence
+
       - run: bin/flatware rspec -r ./spec/flatware_helper.rb
 
       - name: Upload coverage reports to Codecov