ga: ctest uses -C, not --config

.github/workflows/build.yml

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 3bca44e..6eee6a2 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -43,4 +43,4 @@
       - name: test
         working-directory: ${{runner.workspace}}/build
         run: |
-          ctest -v --config Release
+          ctest -v -C Release