Fix typo in SUNDIALS API stability note

Author: FFroehlich

CHANGELOG.md

@@ -91,7 +91,7 @@ The following functionality has been removed without replacement:
   and [SUNDIALS](https://amici.readthedocs.io/en/latest/examples/example_petab/petab_v2.html).
 
   For JAX-based models, the interface can be considered stable;
-  for SUNDIALS-based models, the API nay still change.
+  for SUNDIALS-based models, the API may still change.
 
   SBML- and PySB-based PEtab problems are currently supported.
   For PySB-based PEtab problems, only species and `pysb.Expression` are