fix(0.4/2018-06-09--add_number_of_stamps_to_collections_series.xml): don't prefix a column with table alias in SET clause on PostgreSQL.

This fix is similar to 6d296fd

The error was:
MigrationFailedException: Migration failed for change set classpath:/liquibase/version/0.4/2018-06-09--add_number_of_stamps_to_collections_series.xml::fill-collections_series-number_of_stamps-field::php-coder:
Reason: liquibase.exception.DatabaseException: ERROR: column "cs" of relation "collections_series" does not exist
Position: 37 [Failed SQL: UPDATE collections_series cs SET cs.number_of_stamps = ( SELECT s.quantity FROM series s WHERE s.id = cs.series_id )]

Addressed to #1034

Author: php-coder

src/main/resources/liquibase/version/0.4/2018-06-09--add_number_of_stamps_to_collections_series.xml

@@ -16,7 +16,7 @@
 	<changeSet id="fill-collections_series-number_of_stamps-field" author="php-coder" context="prod-data">
 		<comment>Sets value of number_of_stamps field to number of stamps in a series</comment>
 
-		<sql>
+		<sql dbms="mysql,h2">
 			UPDATE collections_series cs
 			SET cs.number_of_stamps = (
 				SELECT s.quantity
@@ -25,6 +25,16 @@
 			)
 		</sql>
 
+		<!-- In PostgreSQL it is illegal to prefix columns with table alias in the SET clause -->
+		<sql dbms="postgresql">
+			UPDATE collections_series cs
+			SET number_of_stamps = (
+				SELECT s.quantity
+				FROM series s
+				WHERE s.id = cs.series_id
+			)
+		</sql>
+		
 		<rollback>
 			<sql>
 				UPDATE collections_series