Use internal CI runner with access to nims

.gitlab-ci.yml

 test:
-    image: schooft/asapo-client-base
+    image: python:3.6
+    tags:
+        - DESY-intern
     before_script:
         - pip install pytest
         - pip install pytest-mock
         - pip install hdf5plugin
         - pip install numcodecs
+        - pip install --trusted-host nims.desy.de
+          --find-links=http://nims.desy.de/extra/asapo/linux_wheels
+          asapo_producer==20.6.1 asapo_consumer==20.6.1
         - pip install .
     script:
         - pytest -vv