yet another approach

.gitlab-ci.yml

-image: informaticsmatters/rdkit-python3-centos:latest
-
-variables:
-    PIP_CACHE_DIR: "$CI_PROJECT_DIR/.cache/pip"
-
-cache:
-  paths:
-    - .cache/pip
-    - venv/
+image: continuumio/miniconda3:latest
 
 before_script:
-  #- yum install gcc python3-dev python3-pip libxml2-dev libxslt1-dev zlib1g-dev g++
   - python --version
+  - conda create --no-default-packages -n signaturizer_env -y python
+  - conda activate signaturizer_env
+  - conda install -c conda-forge -y rdkit
   - pip install -r requirements.txt
 
 stages: