Update list of maintainers

Miroslav approached me at PyCon DE to remove him from the maintainers
list.

Miro, thanks for all your contributions and your dedication!

Masen was announced as a new maintainer in January 2023.

Thanks for all your contributions, and once again, welcome onboard!

Author: jugmac00

docs/development.rst

@@ -226,5 +226,5 @@ Current maintainers
 -  :user:`Anthony Sottile <asottile>`
 -  :user:`Bernát Gábor <gaborbernat>`
 -  :user:`Jürgen Gmach <jugmac00>`
--  :user:`Miroslav Šedivý <eumiro>`
+-  :user:`Masen Furer <masenf>`
 -  :user:`Oliver Bestwalter <obestwalter>`