updating 3p action tags

Author: Miqueasher

.github/actions/image_scan/action.yml

@@ -32,7 +32,7 @@ runs:
     run: docker logout public.ecr.aws
 
   - name: Run Trivy vulnerability scanner on image
-    uses: aquasecurity/trivy-action@master
+    uses: aquasecurity/trivy-action@e6c2c5e321ed9123bda567646e2f96565e34abe1 # equivalent to `v0.2.4`
     with:
       image-ref: ${{ inputs.image-ref }}
       severity: ${{ inputs.severity }}