dont quote where constraints

public/app/plugins/datasource/postgres/postgres_query.ts

@@ -137,7 +137,7 @@ export default class PostgresQuery {
       value = this.templateSrv.replace(value, this.scopedVars);
     }
 
-    return str + this.quoteIdentifier(constraint.key) + ' ' + operator + ' ' + this.quoteLiteral(value);
+    return str + constraint.key + ' ' + operator + ' ' + value;
   }
 
   interpolateQueryStr(value, variable, defaultFormatFn) {