Merge branch '428-libstdc-11-not-available-on-macos' into 'master'

Resolve "libstdc++11 not available on MacOS"

Closes #428

See merge request AirShowerPhysics/corsika!377

CMakeLists.txt

@@ -106,11 +106,14 @@ include (conan) # self-provided in 'cmake' directory
 #
 # download and build all dependencies
 message (STATUS "Installing dependencies from Conan (this may take some time)...")
+if(NOT APPLE)
+  set(SETTINGS compiler.libcxx=libstdc++11) # not available on MacOS
+endif()
 conan_cmake_run (CONANFILE conanfile.txt
                  BASIC_SETUP CMAKE_TARGETS
                  BUILD missing
                  BUILD_TYPE "Release"
-                 SETTINGS compiler.libcxx=libstdc++11)
+                 SETTINGS ${SETTINGS})
 #
 # add cnpy temporarily. As long as SaveBoostHistogram does not save to parquet directly
 #