Extend RUBY_TEST_TIMEOUT_SCALE on macos-14 and --repeat-count=2

.github/workflows/macos.yml

@@ -108,7 +108,7 @@ jobs:
       - name: Set extra test options
         run: |
           echo "TESTS=$TESTS ${{ matrix.test_opts }}" >> $GITHUB_ENV
-          echo "RUBY_TEST_TIMEOUT_SCALE=3" >> $GITHUB_ENV # With --repeat-count=2, flaky test by timeout occurs frequently for some reason
+          echo "RUBY_TEST_TIMEOUT_SCALE=10" >> $GITHUB_ENV # With --repeat-count=2, flaky test by timeout occurs frequently for some reason
         if: matrix.test_opts
 
       - name: make ${{ matrix.test_task }}