Fix error messaging when data extends beyond forecast date

[kaitejohnson]

This PR closes #202. It uses the assert_no_dates_after_max() check (that wasn't being used, since we removed needing to specify the forecast date from the preprocessing steps!). What it does:

• runs the assertion on the wastewater and count data within the wwinference() function
• updates the assert_no_dates_after_max() to take in args specifying what data is in the date vector and what the max date is
• updates the test of assert_no_dates_after_max() to expect the specific error message written

[github-actions[bot]]

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