Update changelog version

CHANGELOG.md

@@ -1,6 +1,6 @@
 # Changelog
 
-## Unreleased
+## v0.2.1
 
  * BETA: in-silico mutagenesis using ProtTransBertBFD. This computes the likelihood that, according to Bert, a residue in a protein can be a certain amino acid, which can be used as an estimate for the effect of a mutation. This adds two a new `mutagenesis` and a new protocol `plot_mutagenesis` in the `visualize` stages, of which the first one computes the probabilities and writes them to a csv file while the latter visualizes the results as interactive plotly figure.
  * Support `half_precision_model` for `prottrans_bert_bfd` and `prottrans_albert_bfd`