Remove unused mkdocstrings option

Then new `mkdocstrings` version check that the directory exists and
since we don't use it, it doesn't exist, so it fails.

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

mkdocs.yml

@@ -96,7 +96,6 @@ plugins:
       alias_type: redirect
       canonical_version: latest
   - mkdocstrings:
-      custom_templates: templates
       default_handler: python
       handlers:
         python: