fix(gha): remove whitespace from BRANCH in release.yml (#6271)

Author: dbyron-sf

.github/workflows/release.yml

@@ -38,8 +38,9 @@ jobs:
             echo "exactly one branch required to release clouddriver, but there are $NUM_BRANCHES ($BRANCHES)"
             exit 1
           fi
-          echo "exactly one branch ($BRANCHES)"
-          echo BRANCH=$BRANCHES >> $GITHUB_ENV
+          BRANCH=$(echo $BRANCHES | xargs)
+          echo "exactly one branch ($BRANCH)"
+          echo BRANCH="$BRANCH" >> $GITHUB_ENV
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v3
       - name: Set up Docker Buildx