fix: Define HF_HOME to be a mounted/cleaned dir (#3116)

Signed-off-by: Dillon Cullinan <dcullinan@nvidia.com>

.github/workflows/container-validation-backends.yml

@@ -65,6 +65,8 @@ jobs:
             --sccache-bucket "$SCCACHE_S3_BUCKET" \
             --sccache-region "$AWS_DEFAULT_REGION"
       - name: Run pytest
+        env:
+          HF_HOME: /runner/_work/_temp
         run: |
           docker run --runtime=nvidia --rm --gpus all -w /workspace \
             --network host \