Bump thor from 0.19.4 to 0.20.3

Bumps [thor](https://github.com/wycats/thor) from 0.19.4 to 0.20.3.
- [Release notes](https://github.com/wycats/thor/releases)
- [Changelog](https://github.com/erikhuda/thor/blob/master/CHANGELOG.md)
- [Commits](rails/thor@v0.19.4...v0.20.3)

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

Gemfile

@@ -38,7 +38,7 @@ gem 'rails', '4.2.11.1' # locked
 gem 'sass-rails', '5.0.7'
 gem 'splunk-sdk-ruby'
 gem 'sqlite3', '1.3.13'
-gem 'thor', '0.19.4'
+gem 'thor', '0.20.3'
 gem 'time_diff'
 gem 'tiny_tds'
 gem 'turbolinks', '2.5.4' # locked

Gemfile.lock

@@ -290,7 +290,7 @@ GEM
  net-ssh (>= 2.8.0)
  term-ansicolor (1.7.1)
  tins (~> 1.0)
- thor (0.19.4)
+ thor (0.20.3)
  thread_safe (0.3.6)
  tilt (2.0.8)
  time_diff (0.3.0)
@@ -366,7 +366,7 @@ DEPENDENCIES
  splunk-sdk-ruby
  spring (= 2.0.2)
  sqlite3 (= 1.3.13)
- thor (= 0.19.4)
+ thor (= 0.20.3)
  time_diff
  tiny_tds
  turbolinks (= 2.5.4)