Remove dependency on octokit

The [Octokit] gem is not used anywhere in this codebase; it appears there
was originally a GitHub integration planned, but it was removed in
commit 13f460e; but removing this dependency was missed.

This commit removes octokit from our Gemfile so we're not downloading
and installing unused code, and so we don't need to worry about keeping
the dependency up-to-date.

[octokit]: https://github.com/octokit/octokit.rb

Author: lfdebrux

Gemfile

@@ -5,7 +5,6 @@ ruby File.read('.ruby-version').strip
 gem 'activesupport'
 gem 'chronic'
 gem 'http'
-gem 'octokit'
 gem 'rake'
 
 group :test do

Gemfile.lock

@@ -27,23 +27,6 @@ GEM
     domain_name (0.5.20190701)
       unf (>= 0.0.5, < 1.0.0)
     drb (2.2.3)
-    faraday (1.5.1)
-      faraday-em_http (~> 1.0)
-      faraday-em_synchrony (~> 1.0)
-      faraday-excon (~> 1.1)
-      faraday-httpclient (~> 1.0.1)
-      faraday-net_http (~> 1.0)
-      faraday-net_http_persistent (~> 1.1)
-      faraday-patron (~> 1.0)
-      multipart-post (>= 1.2, < 3)
-      ruby2_keywords (>= 0.0.4)
-    faraday-em_http (1.0.0)
-    faraday-em_synchrony (1.0.0)
-    faraday-excon (1.1.0)
-    faraday-httpclient (1.0.1)
-    faraday-net_http (1.0.1)
-    faraday-net_http_persistent (1.2.0)
-    faraday-patron (1.0.0)
     ffi (1.15.5)
     ffi-compiler (1.0.1)
       ffi (>= 1.0.0)
@@ -67,9 +50,6 @@ GEM
     minitest (6.0.5)
       drb (~> 2.0)
       prism (~> 1.5)
-    multipart-post (2.1.1)
-    octokit (4.12.0)
-      sawyer (~> 0.8.0, >= 0.5.3)
     prism (1.9.0)
     public_suffix (4.0.6)
     rake (13.4.2)
@@ -87,11 +67,7 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.13.0)
     rspec-support (3.13.7)
-    ruby2_keywords (0.0.4)
     safe_yaml (1.0.4)
-    sawyer (0.8.2)
-      addressable (>= 2.3.5)
-      faraday (> 0.8, < 2.0)
     securerandom (0.4.1)
     timecop (0.9.1)
     tzinfo (2.0.6)
@@ -113,7 +89,6 @@ DEPENDENCIES
   activesupport
   chronic
   http
-  octokit
   rake
   rexml
   rspec