Bump jekyll-toc from 0.12.2 to 0.13.1 (#45)

Bumps [jekyll-toc](https://github.com/toshimaru/jekyll-toc) from 0.12.2 to 0.13.1.
- [Release notes](https://github.com/toshimaru/jekyll-toc/releases)
- [Commits](toshimaru/jekyll-toc@v0.12.2...v0.13.1)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Author: dependabot-preview[bot]

Gemfile.lock

@@ -185,7 +185,8 @@ GEM
       jekyll-seo-tag (~> 2.0)
     jekyll-titles-from-headings (0.5.3)
       jekyll (>= 3.3, < 5.0)
-    jekyll-toc (0.12.2)
+    jekyll-toc (0.13.1)
+      jekyll (>= 3.7)
       nokogiri (~> 1.9)
     jekyll-watch (2.2.1)
       listen (~> 3.0)