Bump thor from 0.18.1 to 0.20.3

Bumps [thor](https://github.com/wycats/thor) from 0.18.1 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@v0.18.1...v0.20.3)

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

Gemfile.lock

@@ -33,7 +33,7 @@ GEM
     simplecov-html (0.7.1)
     term-ansicolor (1.2.2)
       tins (~> 0.8)
-    thor (0.18.1)
+    thor (0.20.3)
     tins (0.11.0)
 
 PLATFORMS