fix(/collection/{slug}): the query for categories statistic was failing on PostgreSQL.

The error was:
org.springframework.jdbc.BadSqlGrammarException: PreparedStatementCallback; bad SQL grammar [SELECT
CASE WHEN 'ru' = ? THEN COALESCE(c.name_ru, c.name) ELSE c.name END AS name , SUM(s.quantity) AS
counter FROM collections_series cs JOIN series s ON s.id = cs.series_id JOIN categories c ON c.id =
s.category_id WHERE cs.collection_id = ? GROUP BY s.category_id]; nested exception is
org.postgresql.util.PSQLException: ERROR: column "c.name_ru" must appear in the GROUP BY clause or
be used in an aggregate function

Thanks to Pavel Finkelshtein <[email protected]> for help to find a fix.

Part of #1140

Author: php-coder

src/main/resources/sql/category_dao_queries.properties

@@ -65,7 +65,7 @@ category.count_stamps_by_categories = \
     JOIN categories c \
       ON c.id = s.category_id \
    WHERE cs.collection_id = :collection_id \
-GROUP BY s.category_id
+GROUP BY c.id
 
 category.find_ids_by_names = \
    SELECT c.id \