[evolution-ews] Translatable string change

[Milan Crha <mcrha redhat com>]

        Hello,
I just noticed a contribution from a user for evolution-ews [1], which
fixes several typos in the code comments, but also a typo in a
translatable string. I merged the merge request for the next release.

The new string reads:

   Cannot add messages into a Microsoft 365 account from another
   account. Only messages from the same account can be moved/copied
   between the Microsoft 365 folders.

The change was from "an Microsoft" to "a Microsoft" at the beginning of
the sentence.

        Bye,
        Milan

[1] https://gitlab.gnome.org/GNOME/evolution-ews/-/merge_requests/5