sqlglot started doing unnecessary casts to DATE when transpiling to duckdb

[baruchoxman]

Appeared when upgrading from 28.5.0 to 28.6.0

>>> import sqlglot
>>> sqlglot.parse_one("DATE_TRUNC('WEEK', CURRENT_DATE)", "snowflake")
TimestampTrunc(
  this=CurrentDate(),
  unit=Var(this=WEEK),
  input_type_preserved=True)
>>> sqlglot.parse_one("DATE_TRUNC('WEEK', CURRENT_DATE)", "snowflake").sql("duckdb")
"CAST(DATE_TRUNC('WEEK', CURRENT_DATE) AS DATE)"
>>>

It's not a major issue, but the cast to DATE is redundant in this case.

[georgesittas]

Likely an oversight, thanks for reporting.

[georgesittas]

This was intentional after all: #6644. However, I went ahead and made the transpiler a little smarter by checking for date parts / date values: #6771.