refactor: remove blank lines after docstring (#5736)

There shouldn't be any blank lines after the function docstring.
Remove the blank lines to fix this issue.

Co-authored-by: deepsource-autofix[bot] <62050782+deepsource-autofix[bot]@users.noreply.github.com>

docs/main.py

@@ -9,7 +9,6 @@ def define_env(env):
     @env.macro
     def listimages(subdir):
         """Return a listing of all asset files in the provided subdir"""
-
         here = os.path.dirname(__file__)
 
         directory = os.path.join(here, 'docs', 'assets', 'images', subdir)