Remove doc line that is no longer relevant for Python3-only (#7263)

* Fix typo in capture.rst documentation

Rename ``capfsysbinary`` to ``capsysbinary`` as the former does not exist as far as i can see.

* Make Python uppercase in doc/en/capture.rst

Co-authored-by: Hugo van Kemenade <[email protected]>

* Remove the sentence entirely

Co-authored-by: Hugo van Kemenade <[email protected]>
Co-authored-by: Ran Benita <[email protected]>

Author: 3 people

doc/en/capture.rst

@@ -145,8 +145,7 @@ The return value from ``readouterr`` changed to a ``namedtuple`` with two attrib
 
 If the code under test writes non-textual data, you can capture this using
 the ``capsysbinary`` fixture which instead returns ``bytes`` from
-the ``readouterr`` method.  The ``capfsysbinary`` fixture is currently only
-available in python 3.
+the ``readouterr`` method.