fix : missing aidge_onnx dependencies for coverage job

onnxruntime
required for MR aidge_onnx!75

.gitlab/ci/ubuntu_python.gitlab-ci.yml

@@ -76,7 +76,11 @@ coverage:ubuntu_python:
     - source venv/bin/activate
     - which python
     - python -m pip list
-    - python -m pip install numpy coverage requests unittest-xml-reporting pytest onnxruntime
+    - python -m pip install numpy coverage requests unittest-xml-reporting 
+    - >
+      if [[ "$CI_PROJECT_NAME" == "aidge_onnx" ]]; then
+        python -m pip install pytest onnxruntime>=1.18.0
+      fi
   script:
     - cd ${CI_PROJECT_NAME}
     # Retrieve the installation path of the module, since it is installed with pip.