[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

_config.yml

@@ -90,7 +90,7 @@ bibtex_bibfiles:
 sphinx:
   config:
     linkcheck_request_headers:
-      "https://docs.github.com/":
+      'https://docs.github.com/':
         User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux i686; rv:24.0) Gecko/20100101 Firefox/24.0
     html_favicon: images/icons/favicon.ico
     html_last_updated_fmt: '%-d %B %Y'