Add exclusion_condition to expect_row_values_to_have_data_for_every_n_datepart

[gofford]

This PR addresses #140 by adding an exclusion_condition the the row_values_to_have_data_for_every_n_datepart test.

This condition allows the user to specify a criterion for excluding dates from the test output, thereby allowing the test to pass if there are dates that are known to be missing.

exclusion_condition, which defaults to None, is a SQL clause that is appended to the where closing where statement.

Example(s):

tests:
  - dbt_expectations.expect_row_values_to_have_data_for_every_n_datepart:
      date_col: date_day
      date_part: day
      exclusion_condition: date_day not in ('2019-12-25', '2020-12-25', '2021-12-25')

# or equivalently

tests:
  - dbt_expectations.expect_row_values_to_have_data_for_every_n_datepart:
      date_col: date_day
      date_part: day
      exclusion_condition: not(date_part(month, date_day) = 12 and date_part(day, date_day) = 25)

[gofford]

@clausherther in the absence of #139, I'm not 100% of the procedure in place for merging into main. E.g., does this need to incur a version bump, etc.?

Can you advise? I'll then update the remaining items (e.g., docs, version) as required.

[clausherther]

Hi @gofford ! I'll take a more detail look on Monday, but this is great, thanks! Please also update README.md with documentation about the new parameter. I will deal with versioning and the CHANGELOG etc. once it's merged to main.

[clausherther]

@gofford we'll also need an integration test for this parameter somewhere here, as a new instance of the test.

[gofford]

Will do @clausherther. I'll need to look into integration testing in more detail but I should get it turned around this week. Watch this space.

[gofford]

Apologies for the delay. I'll be sorting this out over the next few days.

[clausherther]

FYI, I added an integration test and ran this through our new CI pipeline. LGTM!