feat: configurable tracking image

templates/gitlab-ci-python.yml

@@ -14,6 +14,9 @@
 # Floor, Boston, MA  02110-1301, USA.
 # =========================================================================================
 variables:
+  # variabilized tracking image
+  TBC_TRACKING_IMAGE: "$CI_REGISTRY/to-be-continuous/tools/tracking:master"
+
   # Change pip's cache directory to be inside the project directory since we can
   # only cache local items.
   PIP_CACHE_DIR: "$CI_PROJECT_DIR/.cache/pip"
@@ -532,7 +535,7 @@ variables:
 .python-base:
   image: $PYTHON_IMAGE
   services:
-    - name: "$CI_REGISTRY/to-be-continuous/tools/tracking:master"
+    - name: "$TBC_TRACKING_IMAGE"
       command: ["--service", "python", "4.0.1"]
   # Cache downloaded dependencies and plugins between builds.
   # To keep cache across branches add 'key: "$CI_JOB_NAME"'