Use implicit defaults for most inputs so the GitHub Actions UI shows only the set options

Author: eregon

action.yml

@@ -7,37 +7,27 @@ branding:
 inputs:
   ruby-version:
     description: 'Engine and version to use, see the syntax in the README. Reads from .ruby-version or .tool-versions if unset.'
-    required: false
     default: 'default'
   rubygems:
     description: |
-      The version of RubyGems to use. Either 'default', 'latest', or a version number (e.g., 3.3.5).
+      The version of RubyGems to use. Either 'default' (the default), 'latest', or a version number (e.g., 3.3.5).
       For 'default', no action is taken and the version of RubyGems that comes with Ruby by default is used.
       For 'latest', `gem update --system` is run to update to the latest RubyGems version.
       Similarly, if a version number is given, `gem update --system <version>` is run to update to that version of RubyGems, as long as that version is newer than the one provided by default.
-    required: false
-    default: 'default'
   bundler:
     description: |
       The version of Bundler to install. Either 'none', 'latest', 'Gemfile.lock', or a version number (e.g., 1, 2, 2.1, 2.1.4).
       For 'Gemfile.lock', the version is determined based on the BUNDLED WITH section from the file Gemfile.lock, $BUNDLE_GEMFILE.lock or gems.locked.
-      Defaults to 'Gemfile.lock' if the file exists and 'latest' otherwise.
-    required: false
-    default: 'default'
+      Defaults to 'default', which means 'Gemfile.lock' if the file exists and 'latest' otherwise.
   bundler-cache:
     description: 'Run "bundle install", and cache the result automatically. Either true or false.'
-    required: false
     default: 'false'
   working-directory:
     description: 'The working directory to use for resolving paths for .ruby-version, .tool-versions and Gemfile.lock.'
-    required: false
-    default: '.'
   cache-version:
     description: |
       Arbitrary string that will be added to the cache key of the bundler cache. Set or change it if you need
       to invalidate the cache.
-    required: false
-    default: '0'
 outputs:
   ruby-prefix:
     description: 'The prefix of the installed ruby'

dist/index.js

@@ -13,7 +13,7 @@ const inputDefaults = {
   'ruby-version': 'default',
   'rubygems': 'default',
   'bundler': 'default',
-  'bundler-cache': 'true',
+  'bundler-cache': 'false',
   'working-directory': '.',
   'cache-version': bundler.DEFAULT_CACHE_VERSION,
 }