Add CI minimal CI test for old sympy

The minimal test cannot catch everything but its something.

.gitlab-ci.yml

@@ -101,6 +101,17 @@ minimal-sympy-master:
   tags:
     - docker
 
+minimal-sympy-perhistoric:
+  stage: test
+  except:
+    variables:
+      - $ENABLE_NIGHTLY_BUILDS
+  image: i10git.cs.fau.de:5005/pycodegen/pycodegen/minimal_conda
+  script:
+    - apt install python3-sympy -y
+    - python setup.py quicktest
+  tags:
+    - docker
 
 pycodegen-integration:
   image: i10git.cs.fau.de:5005/pycodegen/pycodegen/full