Add Bundler input

Author: MSP-Greg

README.md

@@ -12,6 +12,7 @@ The action's inputs are shown below:
 - uses: MSP-Greg/setup-ruby-pkgs@v1
   with:
     ruby-version:
+    bundler:
     apt:             # Ubuntu
     brew:            # macOS
     mingw:           # Windows mingw / mswin
@@ -29,6 +30,10 @@ All inputs are optional.
 
 Installs the Ruby version using the code from [ruby/setup-ruby].  The available versions can be found in its [README](https://github.com/ruby/setup-ruby/blob/master/README.md#supported-versions).
 
+### bundler:
+
+Installs Bundler using the code from [ruby/setup-ruby].
+
 ### apt: (Ubuntu)
 
 List of packages to install.  Space delimited. Special options are `_update_` and `_upgrade_`.

action.yml

@@ -4,7 +4,12 @@ author: 'MSP-Greg'
 inputs:
   ruby-version:
     description: 'Ruby version'
-    default: ''
+    required: false
+    default: 'default'
+  bundler:
+    description: 'The version of Bundler to install. Either none, 1, 2, latest or Gemfile.lock. The default tries Gemfile.lock and otherwise uses latest.'
+    required: false
+    default: 'default'
   apt-get:
     description: 'Ubuntu - install packages'
     default: ''