update CHANGELOG

CHANGELOG.rst

@@ -20,7 +20,7 @@ Bug fixes
 Internal changes
 ^^^^^^^^^^^^^^^^
 * Changed french translations with word "pluvieux" to "avec précipitations". (:issue:`1960`, :pull:`1994`).
-* Using different time for `ref` and `hist` is now explicitly forbidden in many bias adjustment methods (e.g. `EmpiricalQuantileMapping`). (:issue:`1903`, :pull:`1995`)
+* Using different time for `ref` and `hist` is now explicitly forbidden in many bias adjustment methods (e.g. `EmpiricalQuantileMapping`). Methods that combine `ref,hist,sim` in a same `map_groups` also require the time arrays to be equal in size. (:issue:`1903`, :pull:`1995`)
 * `streamflow` entry replaced with `q` in ``variables.yml``.  (:issue:`1912`, :pull:`1996`)
 * In order to address 403 (forbidden) request errors when retrieving data from GitHub via ReadTheDocs, the ``nimbus`` class has been modified to use an overloaded `fetch` method that appends a User-Agent header to the request. (:pull:`2001`).
 * Addressed a very rare race condition that can happen if `pytest` is tearing down the test environment when running across multiple workers. (:pull:`1863`).