ci: fix build.yml clone branch

Author: NGPixel

.github/workflows/build.yml

@@ -287,7 +287,7 @@ jobs:
           sudo mkdir -p /workspace
           sudo chown azureuser /workspace
           cd /workspace
-          gh repo clone ietf-tools/datatracker -- --depth=1 --no-tags
+          gh repo clone ietf-tools/datatracker -- --depth=1 --no-tags --branch ${{ github.ref_name }}
           cd datatracker
 
           if [ "$SKIP_TESTS" = "false" ] || [ "$GITHUB_REF_NAME" = "release" ] ; then