Using find_package(Threads REQUIRED) instead of linking pthread directly (#1324)

* Linking to Threads::Threads instead of pthread directly 
* moved rt linking to slsSupportObject and only enable for linux

.gitea/workflows/rh8-native.yml

@@ -21,9 +21,9 @@ jobs:
       - name: Build library 
         run: |
             mkdir build && cd build
-            cmake .. -DSLS_USE_PYTHON=ON -DSLS_USE_TESTS=ON 
+            cmake .. -DSLS_USE_PYTHON=ON -DSLS_USE_TESTS=ON -DSLS_USE_SIMULATOR=ON
             make -j 2 
 
       - name: C++ unit tests
         working-directory: ${{gitea.workspace}}/build
-        run: ctest
+        run: ctest -j1  --rerun-failed --output-on-failure