[bug] Support preprocessing datetime.date date features

[jeffkinnison]

Currently, date feature preprocessing supports datetime.datetime objects, ISO time strings, custom time strings, and int/float timestamps. datetime.date objects, however, are considered invalid and replaced with the fill value despite being valid date features. This update

• adds support for datetime.date objects to DateFeatureMixin.date_to_list
• adds a test for datetime.date support

[github-actions]

Unit Test Results

  6 files  ±0    6 suites  ±0   1h 6m 7s ⏱️ - 3m 18s
34 tests ±0  29 ✔️ ±0    5 💤 ±0  0 ❌ ±0 
88 runs  ±0  72 ✔️ ±0  16 💤 ±0  0 ❌ ±0 

Results for commit 63a1891. ± Comparison against base commit 090918d.

♻️ This comment has been updated with latest results.