Update gitlab-ci.yml

.gitlab-ci.yml

-image: "debian"
+image: "python:3.7"
 
 before_script:
   - wget https://dl.min.io/client/mc/release/linux-amd64/mc
@@ -7,7 +7,12 @@ before_script:
 
 python_run:
   script:
-    - apt update && apt install -y nvidia-cuda-toolkit
+    - apt update && DEBIAN_FRONTEND=noninteractive apt --no-install-recommends -y install ca-certificates gnupg2 apt-transport-https sed
+    - sed -i 's/deb.debian.org/mirror.cs.uni-duesseldorf.de/g' /etc/apt/sources.list && \
+      sed -i 's/security.debian.org/mirror.cs.uni-duesseldorf.de/g' /etc/apt/sources.list && \
+      sed -i 's/main/main contrib non-free/g' /etc/apt/sources.list
+    - DEBIAN_FRONTEND=noninteractive apt --no-install-recommends -y install nvidia-cuda-toolkit
+    - apt clean && apt autoremove && rm -rf /var/lib/apt/lists/*
     - pip install flair
     - pip install torch
     - pip install pandas