sphinx-lint: trailing whitespace

Fix all instances of trailing-whitespace as reported by 'make sphinx-lint'.

(From yocto-docs rev: 7776550a190060221a8cc913e470edf5349b6829)

Signed-off-by: Trevor Woerner <twoerner@gmail.com>
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

documentation/migration-guides/migration-4.0.rst

@@ -143,7 +143,7 @@ Python changes
   The new Python packaging classes that should be used are
   :ref:`python_flit_core <ref-classes-python_flit_core>`,
   :ref:`python_setuptools_build_meta <ref-classes-python_setuptools_build_meta>`
-  and :ref:`python_poetry_core <ref-classes-python_poetry_core>`.  
+  and :ref:`python_poetry_core <ref-classes-python_poetry_core>`.
 
 - The :ref:`setuptools3 <ref-classes-setuptools3>` class ``do_install()`` task now
   installs the ``wheel`` binary archive. In current versions of ``setuptools`` the