test on a g4dn.xlarge @ 53 cents an hour

.github/workflows/gpu-runner.yaml

@@ -23,7 +23,7 @@ jobs:
           provider: "aws"
           action: "start"
           aws_image_id: ami-0f7c4a792e3fb63c8
-          aws_instance_type: c7i.xlarge
+          aws_instance_type: g4dn.xlarge
           aws_region_name: us-east-1
           aws_home_dir: /home/ubuntu
         env:
@@ -41,13 +41,19 @@ jobs:
       - name: Print Docker details
         run: "docker version || true"
 
+      - name: Check for nvidia-smi
+        run: "nvidia-smi"
+
       - name: "Setup Micromamba"
         uses: mamba-org/setup-micromamba@v1
         with:
           environment-file: environment.yml
           environment-name: openfe_env
           init-shell: bash
 
+      - name: "Check if OpenMM can get a GPU"
+        run: python -m openmm.testInstallation
+
       - name: "Install GUFE from main@HEAD"
         run: python -m pip install --no-deps git+https://github.com/OpenFreeEnergy/gufe@main
         shell: bash -el {0}