Bug 1857012 - Use taskcluster-built python for addon task r=jmaher

Differential Revision: https://phabricator.services.mozilla.com/D190083

taskcluster/ci/addon/kind.yml

@@ -4,10 +4,17 @@
 ---
 loader: gecko_taskgraph.loader.transform:loader
 
+kind-dependencies:
+    # non-system python
+    - toolchain
+
 transforms:
     - gecko_taskgraph.transforms.job:transforms
     - gecko_taskgraph.transforms.task:transforms
 
+job-defaults:
+    use-system-python: false
+
 jobs:
     tps-xpi:
         description: Build the TPS add-on