fix(parser): allow VERSION in ALTER column clauses (#2530)

VERSION is non-reserved, but restricted legacy productions reject it in DROP COLUMN and USING clauses. Accept the token in those productions and cover both PostgreSQL corpus cases.

Author: minleejae

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -2244,6 +2244,7 @@ Token KeywordOrIdentifier():
       | tk = <K_STRING>
       | tk = <K_DATA>
       | tk = <K_TYPE>
+      | tk = <K_VERSION>
     )
     { return tk; }
 }
@@ -12065,7 +12066,7 @@ List<String> CreateParameter():
         |
         (
             //@todo: implement a proper identifier
-            (tk=<S_IDENTIFIER> | tk=<S_QUOTED_IDENTIFIER> | tk=<K_NAME>)
+            (tk=<S_IDENTIFIER> | tk=<S_QUOTED_IDENTIFIER> | tk=<K_NAME> | tk=<K_VERSION>)
             { retval+=tk.image; }
 
             [

src/test/java/net/sf/jsqlparser/statement/alter/AlterTest.java

@@ -648,6 +648,15 @@ public void testAlterTableAlterColumnDropNotNullIssue918() throws JSQLParserExce
                 "ALTER TABLE \"user_table_t\" ALTER COLUMN name DROP NOT NULL");
     }
 
+    @Test
+    public void testAlterTableVersionColumn() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed(
+                "ALTER TABLE test_table DROP COLUMN version, DROP COLUMN other_column");
+        assertSqlCanBeParsedAndDeparsed(
+                "ALTER TABLE test_table ALTER COLUMN version TYPE VARCHAR(32) "
+                        + "USING version::VARCHAR(32)");
+    }
+
     @Test
     public void testAlterTableRenameColumn() throws JSQLParserException {
         // With Column Keyword