Bump irb from 1.8.3 to 1.9.1 (#203)

Bumps [irb](https://github.com/ruby/irb) from 1.8.3 to 1.9.1.
- [Release notes](https://github.com/ruby/irb/releases)
- [Commits](https://github.com/ruby/irb/compare/v1.8.3...v1.9.1)

---
updated-dependencies:
- dependency-name: irb
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Gemfile

@@ -5,5 +5,5 @@ source "https://rubygems.org"
 gem "rugged", "~> 1.5.1"
 gem "liquid", "~> 5.4"
 
-gem "irb", "~> 1.8", :group => [:development]
+gem "irb", "~> 1.9", :group => [:development]
 gem "rdoc", "~> 6.4", :group => [:development]

Gemfile.lock

@@ -2,7 +2,7 @@ GEM
   remote: https://rubygems.org/
   specs:
     io-console (0.6.0)
-    irb (1.8.3)
+    irb (1.9.1)
       rdoc
       reline (>= 0.3.8)
     liquid (5.4.0)
@@ -10,16 +10,16 @@ GEM
       stringio
     rdoc (6.5.0)
       psych (>= 4.0.0)
-    reline (0.3.9)
+    reline (0.4.1)
       io-console (~> 0.5)
     rugged (1.5.1)
-    stringio (3.0.8)
+    stringio (3.1.0)
 
 PLATFORMS
   x86_64-linux
 
 DEPENDENCIES
-  irb (~> 1.8)
+  irb (~> 1.9)
   liquid (~> 5.4)
   rdoc (~> 6.4)
   rugged (~> 1.5.1)