gha/bin-image: Fix dco running on non-v tags

bin-image workflow was failing for the new docker tags
(`docker-v29.0.0-rc.2`) because it wasn't correctly picked up by the
condition that should filter out tags.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

.github/workflows/bin-image.yml

@@ -37,7 +37,7 @@ env:
 
 jobs:
   validate-dco:
-    if: ${{ !startsWith(github.ref, 'refs/tags/v') }}
+    if: ${{ !startsWith(github.ref, 'refs/tags/') }}
     uses: ./.github/workflows/.dco.yml
 
   prepare: