date type between mssql and mysql not working.

# env
embulk v0.9.23
java openjdk version "1.8.0_252"

# situation
(MSSQL)
nullable *date* type
->
(MYSQL)
nullable date type

# issue
destination date columns are filled with NULL value.
even all the source columns have values.

``` yaml
in:
type: sqlserver
host: ***
user: ***
password: ***
database: ***
query: |-
SELECT
[sdate],
***
FROM *** WITH (NOLOCK)
out:
type: mysql
host: ***
user: ***
password:***
database: ***
table: ***
mode: merge_direct
options: {useUnicode: true, characterEncoding: UTF-8}
column_options:
sdate: {type: date null}

```