Test an example configuration for py3-* jobs without industrial_ci

.gitlab-ci.yml

@@ -47,3 +47,8 @@ simple_ros_auto_rules_melodic_noetic_test:
   extends: .simple_ros_test
   variables:
     TEMPLATE_TO_USE: test/auto_rules_melodic_noetic.yml
+
+simple_ros_only_py3_test:
+  extends: .simple_ros_test
+  variables:
+    TEMPLATE_TO_USE: test/only_py3.yml

test/only_py3.yml

+include: ci-templates/core.yml
+
+py3-flake8:
+  extends: .py3-flake8
+
+py3-flake8_extended:
+  extends: .py3-flake8_extended
+
+py3-security:
+  extends: .py3-security