CI fix

Author: Nat!

.github/workflows/cmake-errors.yml

@@ -98,7 +98,7 @@ jobs:
           
       - name: Clone mulle-core repository
         run: |
-          git clone https://github.com/mulle-core/mulle-core.git "${MULLE_CORE_SRC_DIR}"
+          git clone https://github.com/mulle-core/mulle-core.git "${steps.set-install-dir.outputs.MULLE_CORE_SRC_DIR}"
           
       - name: Configure, build and install mulle-core with CMake
         working-directory: "${steps.set-install-dir.outputs.MULLE_CORE_SRC_DIR}"