The following liquibase changeset does not work as expected

```xml
        <createTable tableName="test">
            <column name="id" type="SERIAL">
                <constraints nullable="false" primaryKey="true"/>
            </column>
        </createTable>
```

This changeset results in sql

```sql
CREATE TABLE test (id INTEGER NOT NULL, CONSTRAINT TEST_PKEY PRIMARY KEY (id));
```

In liquibase 3.6.3 and earlier the type `SERIAL` was used for the column which means that a sequence is automatically included.

This issue seems to be caused by #874
It appears that SERIAL columns are replaced by INT, however liquibase does reconize that this column type is an auto increment column.

It would be acceptible if the generated sql would be

```sql
CREATE TABLE test (id INTEGER GENERATED BY DEFAULT AS IDENTITY NOT NULL, CONSTRAINT TEST_PKEY PRIMARY KEY (id));
```


* @param string The database function name to test
     * @param database A database object to test against
     * @return see above
     */
    protected boolean isCurrentDateTimeFunction(String string, Database database) {
        return string.toLowerCase(Locale.US).startsWith("current_timestamp")
                || string.toLowerCase(Locale.US).startsWith(DatabaseFunction.CURRENT_DATE_TIME_PLACE_HOLDER)
                || database.getCurrentDateTimeFunction().toLowerCase(Locale.US).equals(string.toLowerCase(Locale.US));
    }
    public void finishInitialization(String originalDefinition) {
        this.rawDefinition = originalDefinition;
    }
    /**
     * Removes any trailing ".0[...]0" from the end of a number
     * @param value the number (in String form) to format
     * @return the formatted number
     */
    protected String formatNumber(String value) {
        if (value == null) {
            return null;
        }
        return value.replaceFirst("\\.0+$", "");
    }
    /**
     * Returns one of the four basic data types for use in LoadData: BOOLEAN, NUMERIC, DATE or STRING
     * @return one of the above Strings
     */
    public abstract LoadDataChange.LOAD_DATA_TYPE getLoadTypeName();
}