v16

From the changelog:

• 23 January 2025: Include a new mlr_lineage_fitness coloring. This uses live estimates of lineage fitness from nextstrain.org/sars-cov-2/forecasts to provide a strain-level coloring to the tree. The lineage fitness estimates are automatically updated as new data comes in and so this coloring should stay current. PR 1169

• 23 January 2025: Remove previous fitness-related colorings of mutational_fitness, logistic_growth and current_frequency (used by logistic growth). The new mlr_lineage_fitess should be more accurate / more current than these previous approaches. PR 1169