Fix Sphinx warning in module build docs

The "Alternatively, install and use twine directly::" line introduced a
literal block marker with no following indented block, causing a Sphinx
warning that fails the docs CI build (-W flag). Change it to a plain
sentence.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hjmjohnson

docs/Build_ITK_Module_Python_packages.rst

@@ -304,7 +304,7 @@ a partial upload failure.
 Manual Upload
 -------------
 
-Alternatively, install and use ``twine`` directly::
+Alternatively, install and use ``twine`` directly.
 
 Test on TestPyPI first::