docs: fix flake8 lint errors in bigframes_queries

Author: shuoweil

bigquery/bigframes/bigframes_queries.py

@@ -30,6 +30,7 @@ def query_standard_sql():
     df = bpd.read_gbq(sql)
 
     # Run a query after explicitly specifying a project.
+    project_id = "your-project-id"
     bpd.options.bigquery.project = project_id
     df = bpd.read_gbq(sql)
     # [END bigquery_bigframes_query]

bigquery/bigframes/bigframes_queries_test.py

@@ -12,9 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import pytest
-
 import bigframes_queries
+import pytest
 
 
 @pytest.mark.skip(