fix typo

Author: johan456789

src/python-modules.md

@@ -7,7 +7,7 @@ If your add-on uses a standard Python module that has not
 been included, or a package from PyPI, then your add-on will need to bundle the module.
 
 For pure Python modules, this is usually as simple as putting them in a
-subfolder, and adjusting sys.path. For modules that that require C extensions
+subfolder, and adjusting sys.path. For modules that require C extensions
 such as numpy, things get a fair bit more complicated, as you'll need to bundle
 the different module versions for each platform, and ensure you're bundling a
 version that is compatible with the version of Python Anki is packaged with.