fix pg not support function now(integer)

[caoyanan666]

https://github.com/alibaba/nacos/pull/12244 引入了now转成now(3)，pg会报错 org.springframework.jdbc.BadSqlGrammarException: PreparedStatementCallback; bad SQL grammar []; nested exception is org.postgresql.util.PSQLException: ERROR: function now(integer) does not exist Hint: No function matches the given name and argument types. You might need to add explicit type casts.

[CLAassistant]

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[HaiFongPan]

LGTM

[caoyanan666]

@KomachiSion 帮忙review下