pull-updates: Fix pulling new upstream versions

Commit 5802517d "pull-updates: Push all local refs atomically" broke
pushing multiple refs when pulling updates (that ism when pulling a
new upstream version) due to excessive quoting.

    $ git push --follow-tags --atomic ${CI_AUTH_PROJECT_URL} "$BRANCHES"
    fatal: invalid refspec 'debian/buster
    debian/buster-security
    pristine-lfs
    upstream/buster'

Let `$BRANCH` get expanded to multiple arguments rather than passing all
of them as a single argument.

Signed-off-by: Ritesh Raj Sarraf <ritesh.sarraf@collabora.com>

ci-package-builder.yml

@@ -250,8 +250,8 @@ pull-updates:
         "upstream/*"
         "pristine-lfs"
       )
-    - echo "🔼 Pushing the updated local branches $BRANCHES"
-    - git push --follow-tags --atomic ${CI_AUTH_PROJECT_URL} "$BRANCHES"
+    - echo "🔼 Pushing the updated local branches" $BRANCHES
+    - git push --follow-tags --atomic ${CI_AUTH_PROJECT_URL} $BRANCHES
 
 merge-updates:
   stage: merge