Fixed a typo (thanks to @ThaPwned)

Author: Ayuto

addons/source-python/packages/source-python/plugins/manager.py

@@ -216,7 +216,7 @@ def unload(self, plugin_name):
         try:
             plugin._unload()
         except:
-            except_hooks.print_exceptions()
+            except_hooks.print_exception()
 
         self._remove_modules(plugin_name)
         del self[plugin_name]