Updating the strata to include the finalized BCRs including new BCR numbers

[AdamCSmithCWS]

Relatively small update to bring the most recent BCR definitions and names.

• Northern BCRs were renumbered so that BCRs 3, 6, 7, and 8 are now renumbered 68 through 77. The other bcr numbers have not changed. For details, see the primary BCR spatial layers curated by Birds Canada.

• Includes a small correction to the parameterisation of the hyperparameter trajectory in the spatial and hierarchical first difference models. The error did not affect any of the values called by the package, only a derived parameter that is in the model but never called by the package.
• Also includes a few tweaks to the coding of the generate_indices, generate_trends, and plot_indices functions to account for some deprecations in tidy_select.