Set IsolationLevel PROCESS

Author: slozier

tests/IronPython.Tests/Cases/IronPythonCasesManifest.ini

@@ -65,6 +65,9 @@ Reason=New test needs to be written for new csharp version
 Ignore=true
 Reason=Assertion error
 
+[IronPython.test_memory]
+IsolationLevel=PROCESS # to avoid having a long list of object subtypes
+
 [IronPython.test_number]
 Timeout=300000 # 5 minute timeout - slow on macOS