message: Remove redundant UTC casts
diff: @@ -478,14 +478,14 @@ class PostgresBaseEngineSpec(BaseEngineSpec):
  time_grain_functions = {
  None: '{col}',
  - 'PT1S': "DATE_TRUNC('second', {col}) AT TIME ZONE 'UTC'",
  - 'PT1M': "DATE_TRUNC('minute', {col}) AT TIME ZONE 'UTC'",
  - 'PT1H': "DATE_TRUNC('hour', {col}) AT TIME ZONE 'UTC'",
  - 'P1D': "DATE_TRUNC('day', {col}) AT TIME ZONE 'UTC'",
  - 'P1W': "DATE_TRUNC('week', {col}) AT TIME ZONE 'UTC'",
  - 'P1M': "DATE_TRUNC('month', {col}) AT TIME ZONE 'UTC'",
  - 'P0.25Y': "DATE_TRUNC('quarter', {col}) AT TIME ZONE 'UTC'",
  - 'P1Y': "DATE_TRUNC('year', {col}) AT TIME ZONE 'UTC'",
  + 'PT1S': "DATE_TRUNC('second', {col})",
  + 'PT1M': "DATE_TRUNC('minute', {col})",
  + 'PT1H': "DATE_TRUNC('hour', {col})",
  + 'P1D': "DATE_TRUNC('day', {col})",
  + 'P1W': "DATE_TRUNC('week', {col})",
  + 'P1M': "DATE_TRUNC('month', {col})",
  + 'P0.25Y': "DATE_TRUNC('quarter', {col})",
  + 'P1Y': "DATE_TRUNC('year', {col})",
  }
  @classmethod
  