ci: switch GGUF model cache key to URL hash

Replaces the use of the ETag header with a SHA-256 hash of the GGUF model URL for cache key generation in the workflow. This improves reliability by avoiding dependency on remote server ETag support.

Author: andinux

.github/workflows/main.yml

@@ -15,19 +15,19 @@ env:
 jobs:
   download-model:
     outputs:
-      cache-key: gguf-${{ steps.meta.outputs.etag }}
+      cache-key: gguf-${{ steps.meta.outputs.hash }}
     name: Download GGUF model
     runs-on: ubuntu-22.04
     steps:
-      - name: Fetch GGUF metadata
+      - name: Compute model URL hash
         id: meta
         run: |
-          etag=$(curl -sI "${{ env.GGUF_MODEL_URL }}" | tr -d '\r' | awk 'tolower($1)=="etag:" {print $2}' | tr -d '"')
-          if [ -z "$etag" ]; then
-            echo "Failed to determine model ETag" >&2
-            exit 1
+          if command -v sha256sum >/dev/null 2>&1; then
+            hash=$(echo -n "${{ env.GGUF_MODEL_URL }}" | sha256sum | cut -d' ' -f1)
+          else
+            hash=$(echo -n "${{ env.GGUF_MODEL_URL }}" | shasum -a 256 | cut -d' ' -f1)
           fi
-          echo "etag=$etag" >> "$GITHUB_OUTPUT"
+          echo "hash=$hash" >> "$GITHUB_OUTPUT"
 
       - name: Prepare model directory
         run: mkdir -p "${{ env.GGUF_MODEL_DIR }}"
@@ -37,7 +37,7 @@ jobs:
         uses: actions/cache@v4
         with:
           path: ${{ env.GGUF_MODEL_DIR }}/${{ env.GGUF_MODEL_NAME }}
-          key: gguf-${{ steps.meta.outputs.etag }}
+          key: gguf-${{ steps.meta.outputs.hash }}
 
       - name: Download GGUF model
         if: steps.cache.outputs.cache-hit != 'true'