Update enrichment test to use {{}} template

Author: aIbrahiim

sdks/python/apache_beam/yaml/extended_tests/data/enrichment.yaml

@@ -62,7 +62,7 @@ pipelines:
               project: apache-beam-testing
               table_name: "{BQ_TABLE}"
               fields: ['label']
-              row_restriction_template: "label = '{}'"
+              row_restriction_template: "label = '{{}}'"
             timeout: 30
 
         - type: MapToFields