tests: run parallel tests in separate processes

library compilation and execution failing the second time if not

.github/workflows/continuous-integration.yml

@@ -266,7 +266,7 @@ jobs:
             echo "Debug: ccache statistics (prior to the build):"
             ccache -s
             cd /compiler
-            pip install pytest
+            pip install pytest pytest-forked
             rm -rf /build
             export PYTHONPATH=""
             make PARALLEL_EXECUTION_ENABLED=ON CCACHE=ON BUILD_DIR=/build test test-dataflow

compiler/tests/python/test_compilation.py

@@ -193,6 +193,8 @@ def test_lib_compile_reload_and_run(mlir_input, args, expected_result, keyset_ca
         pytest.param(LibrarySupport, id="Library"),
     ],
 )
+# TODO: #505
+@pytest.mark.forked
 def test_compile_and_run_auto_parallelize(
     mlir_input, args, expected_result, keyset_cache, EngineClass
 ):