Bug 1534578 - Upgrade macosx64 taskcluster tasks to python 3.7. r=ahal

Bug 1501497 deployed python 3.7 on mac workers, while leaving 3.6
around... except on reimaged workers, which only have 3.7 available.

Differential Revision: https://phabricator.services.mozilla.com/D31191

--HG--
extra : moz-landing-system : lando

taskcluster/taskgraph/transforms/job/python_test.py

@@ -39,7 +39,7 @@ def configure_python_test(config, job, taskdesc):
 
     if worker['os'] == 'macosx' and run['python-version'] == 3:
         # OSX hosts can't seem to find python 3 on their own
-        run['python-version'] = '/tools/python36/bin/python3.6'
+        run['python-version'] = '/tools/python37/bin/python3.7'
         if job['worker-type'].endswith('1014'):
             run['python-version'] = '/usr/local/bin/python3'
 

taskcluster/taskgraph/transforms/job/run_task.py

@@ -129,7 +129,7 @@ def generic_worker_run_task(config, job, taskdesc):
     if is_win:
         command = ['C:/mozilla-build/python3/python3.exe', 'run-task']
     elif is_mac:
-        command = ['/tools/python36/bin/python3.6', 'run-task']
+        command = ['/tools/python37/bin/python3.7', 'run-task']
         if job['worker-type'].endswith('1014'):
             command = ['/usr/local/bin/python3', 'run-task']
     else: