Bump octokit from 4.12.0 to 4.13.0 (#1340) [ci skip]

Bumps [octokit](https://github.com/octokit/octokit.rb) from 4.12.0 to 4.13.0.
- [Release notes](https://github.com/octokit/octokit.rb/releases)
- [Changelog](https://github.com/octokit/octokit.rb/blob/master/RELEASE.md)
- [Commits](https://github.com/octokit/octokit.rb/compare/v4.12.0...v4.13.0)

Signed-off-by: dependabot[bot] <support@dependabot.com>

Gemfile

@@ -59,7 +59,7 @@ gem "kaminari", "~> 1.1"
 gem "libhoney", "~> 1.10"
 gem "liquid", "~> 4.0"
 gem "nokogiri", "~> 1.8"
-gem "octokit", "~> 4.12"
+gem "octokit", "~> 4.13"
 gem "omniauth", "~> 1.8"
 gem "omniauth-github", "~> 1.3"
 gem "omniauth-twitter", "~> 1.4"

Gemfile.lock

@@ -600,7 +600,7 @@ GEM
       multi_json (~> 1.3)
       multi_xml (~> 0.5)
       rack (>= 1.2, < 3)
-    octokit (4.12.0)
+    octokit (4.13.0)
       sawyer (~> 0.8.0, >= 0.5.3)
     omniauth (1.8.1)
       hashie (>= 3.4.6, < 3.6.0)
@@ -980,7 +980,7 @@ DEPENDENCIES
   memory_profiler (~> 0.9)
   nakayoshi_fork
   nokogiri (~> 1.8)
-  octokit (~> 4.12)
+  octokit (~> 4.13)
   omniauth (~> 1.8)
   omniauth-github (~> 1.3)
   omniauth-twitter (~> 1.4)