feat(setup-trivy): use latest as default version (#15)

Using the "latest" released version of Trivy as the default version.
We always first resolve latest to an actual version to allow the cache to work properly.

Reviewed-on: t.behrendt/trivy-actions#15
Reviewed-by: branch-buddy <branch-buddy@t00n.de>
Co-authored-by: Timo Behrendt <t.behrendt@t00n.de>
Co-committed-by: Timo Behrendt <t.behrendt@t00n.de>

setup-trivy/action.yaml

@@ -9,7 +9,7 @@ inputs:
   version:
     description: "Trivy version to download (e.g., latest)"
     required: false
-    default: "v0.66.0"
+    default: "latest"
 
 runs:
   using: "composite"
@@ -27,21 +27,32 @@ runs:
             ;;
         esac
         echo "ARCH=$ARCH" >> $GITHUB_OUTPUT
+    - name: Resolve version
+      shell: bash
+      id: version
+      run: |
+        set -e
+        if [ "${{ inputs.version }}" = "latest" ]; then
+          VERSION=$(curl -s https://api.github.com/repos/aquasecurity/trivy/releases/latest | jq -r '.tag_name')
+        else
+          VERSION="${{ inputs.version }}"
+        fi
+        echo "VERSION=$VERSION" >> $GITHUB_OUTPUT
     - name: Cache Trivy binary
       id: cache-trivy
       uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
       with:
         path: /usr/local/bin/trivy
-        key: trivy-${{ inputs.version }}-${{ steps.arch.outputs.arch }}
+        key: trivy-${{ steps.version.outputs.version }}-${{ steps.arch.outputs.arch }}
         restore-keys: |
-          trivy-${{ inputs.version }}-${{ steps.arch.outputs.arch }}
+          trivy-${{ steps.version.outputs.version }}-${{ steps.arch.outputs.arch }}
     - name: Download and install Trivy
       if: steps.cache-trivy.outputs.cache-hit != 'true'
       shell: bash
       run: |
         set -e
 
-        VERSION="${{ inputs.version }}"
+        VERSION="${{ steps.version.outputs.version }}"
 
         mkdir -p /usr/local/bin