Typo in version string

See also: https://github.com/nwg-piotr/nwg-panel/issues/281

Pascal Jäger <pascal.jaeger@leimstift.de> (2024-01-10)

--- a/setup.py
+++ b/setup.py
@@ -8,7 +8,7 @@ def read(f_name):
 
 setup(
     name='nwg-panel',
-    version='0.9.20 ',
+    version='0.9.20',
     description='GTK3-based panel for sway and Hyprland Wayland compositors',
     packages=find_packages(),
     include_package_data=True,
