Lump all Northwestern Crow counts into American Crow

[AdamCSmithCWS]

The 2024 data release has a small error. The two codes that related to Northwestern Crow (no longer considered a species) were removed from the species list, but the counts were not re-allocated to American Crow.

A very small change in the fetch_bbs_data() can replace the aou codes for Northwestern Crow (4890) and for unidentified Northwestern/American Crow (4882) with the code for American Crow (4880).

This should be done in a way so that all of the data accessible to users, including the un-stratified data load_bbs_data() will be corrected.