use current python executable to run tests with CLI version

test/conftest.py

 from cgi import test
-import os, subprocess
+import os, subprocess, sys
 
 class KTH_WL:
     swf_file = "workloads/KTH-SP2-1996-2.1-cln.swf"
@@ -30,7 +30,7 @@ def run_script(delim, threshold,
     out_dir = os.path.abspath(f'test-out/{test_name}')
     create_dir_rec_if_needed(out_dir)
 
-    args = ['swf2userSessions', f'--{delim}', str(threshold), 
+    args = [sys.executable, 'swf2userSessions/swf2sessions.py', f'--{delim}', str(threshold), 
             '-q', input_swf, out_dir]
     if graph:
         args.append("--graph")