build system: use asan on the CI

.github/workflows/build.yml

@@ -23,7 +23,7 @@ jobs:
       env:
         CXX: ${{ matrix.compiler }}
       run: |
-        cmake -DENTT_BUILD_TESTING=ON -DENTT_BUILD_LIB=ON -DENTT_BUILD_EXAMPLE=ON ..
+        cmake -DENTT_USE_ASAN=ON -DENTT_BUILD_TESTING=ON -DENTT_BUILD_LIB=ON -DENTT_BUILD_EXAMPLE=ON ..
         make -j4
     - name: Run tests
       working-directory: build