Use a container image with git available

Author: namannimmo10

.github/workflows/httomolibgpu_tests_run_iris.yml

@@ -8,7 +8,7 @@ jobs:
   iris-gpu:
     runs-on: iris-gpu
     container:
-      image: nvidia/cuda:12.6.3-devel-ubi8
+      image: ghcr.io/diamondlightsource/httomolibgpu:dockerfile
       env:
         NVIDIA_VISIBLE_DEVICES: ${{ env.NVIDIA_VISIBLE_DEVICES }}
       options: --gpus all --runtime=nvidia