Bump jekyll-toc from 0.14.0 to 0.15.0 (#59)

Bumps [jekyll-toc](https://github.com/toshimaru/jekyll-toc) from 0.14.0 to 0.15.0.
- [Release notes](https://github.com/toshimaru/jekyll-toc/releases)
- [Commits](toshimaru/jekyll-toc@v0.14.0...v0.15.0)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Gemfile.lock

@@ -189,7 +189,7 @@ GEM
       jekyll-seo-tag (~> 2.0)
     jekyll-titles-from-headings (0.5.3)
       jekyll (>= 3.3, < 5.0)
-    jekyll-toc (0.14.0)
+    jekyll-toc (0.15.0)
       jekyll (>= 3.8)
       nokogiri (~> 1.10)
     jekyll-watch (2.2.1)