[Darwin][Sanitizer] Lower Python requirement for iOS simulator testing

Lower Python requirements: 3.7 -> 3.6

Workaround introduced in: ebd8eee

Author: Julian Lettner

compiler-rt/test/sanitizer_common/ios_commands/iossim_run.py

@@ -23,7 +23,7 @@
     os.environ["SIMCTL_CHILD_" + e] = os.environ[e]
 
 find_atos_cmd = 'xcrun -sdk iphonesimulator -f atos'
-atos_path = subprocess.run(find_atos_cmd.split(), capture_output=True, check=True).stdout.decode().strip()
+atos_path = subprocess.run(find_atos_cmd.split(), stdout=subprocess.PIPE, stderr=subprocess.PIPE, check=True).stdout.decode().strip()
 for san in ['ASAN', 'TSAN', 'UBSAN', 'LSAN']:
   os.environ[f'SIMCTL_CHILD_{san}_SYMBOLIZER_PATH'] = atos_path