DBZ-6194 Use CHARSET for alterByConvertCharset clause

debezium-ddl-parser/src/main/antlr4/io/debezium/ddl/parser/mysql/generated/MySqlParser.g4

@@ -715,7 +715,7 @@ alterSpecification
     | ENABLE KEYS                                                   #alterByEnableKeys
     | RENAME renameFormat=(TO | AS)? (uid | fullId)                 #alterByRename
     | ORDER BY uidList                                              #alterByOrder
-    | CONVERT TO CHARACTER SET charsetName
+    | CONVERT TO (CHARSET | CHARACTER SET) charsetName
       (COLLATE collationName)?                                      #alterByConvertCharset
     | DEFAULT? CHARACTER SET '=' charsetName
       (COLLATE '=' collationName)?                                  #alterByDefaultCharset

debezium-ddl-parser/src/test/resources/mysql/examples/ddl_alter.sql

@@ -44,6 +44,7 @@ alter table add_test drop foreign key if exists fk;
 alter table add_test drop constraint if exists cons;
 alter table add_test wait 100 add column col1 int not null;
 alter table default.task add column xxxx varchar(200) comment 'cdc test';
+ALTER TABLE `hcore`.comments COLLATE='utf8mb4_general_ci', CONVERT TO CHARSET UTF8MB4;
 #end
 #begin
 -- Alter database