Merge branch 'gmm-test' into 'master'

Add basic test for GMM finder

See merge request !10

CI/tests/GMM/CMakeLists.txt

+find_package(GMM REQUIRED)
+
+add_executable(test_gmm "test_gmm.cc")
+target_link_libraries(test_gmm PRIVATE GMM::GMM)
+add_test(NAME test_gmm COMMAND test_gmm)
+
+

CI/tests/GMM/test_gmm.cc

+#include <gmm/gmm.h>
+
+int main(int argc, char *argv[])
+{
+    gmm::csc_matrix<double> mat;
+    return 0;
+}