Support for Mise's recommended table format

[stormwatch]

Describe the problem as clearly as you can

Specifying a Ruby version supports the simple syntax like showed in Bundler's documentation:

ruby = '3.4.6'

This is a request to also support Mise's recommended table format

Did you try upgrading rubygems & bundler?

Yes.

Post steps to reproduce the problem

Declare your ruby version in your Gemfile

Following Bundler's documentation specifying a Ruby version, specify your Ruby version as follows:

ruby file: "mise.toml"

Create a mise.toml file in the yet unsupported table format

Save the following as mise.toml in the same directory as the Gemfile

[tools]
ruby = { version = "3.4.6", postinstall = "ruby-post-install" }

You may remove the postinstall section if you don't want to run a post-installation script but keep the format with enclosing braces in order to trigger the bug; i.e. you can write a mise.toml like in this alternative:

[tools]
ruby = { version = "3.4.6" }

Which command did you run?

bundle check --verbose

What were you expecting to happen?

❯ bundle check --verbose
Found no changes, using resolution from the lockfile
The Gemfile's dependencies are satisfied

What happened instead?

❯ bundle check --verbose

[!] There was an error parsing `Gemfile`: { is not a valid requirement on the Ruby version. Bundler cannot continue.

 #  from /Users/eze/ejercicios/katas/Template Strings/Gemfile:2
 #  -------------------------------------------
 #  source 'https://rubygems.org'
 >  ruby file: 'mise.toml'
 #
 #  -------------------------------------------

If not included with the output of your command, run bundle env and paste the output below

## Environment

```
Bundler       2.7.2
  Platforms   ruby, x86_64-darwin-21
Ruby          3.4.6p54 (2025-09-16 revision dbd83256b1cec76c69756ecb8758b9e1079833de) [x86_64-darwin-21]
  Full Path   /Users/eze/.local/share/mise/installs/ruby/3.4.6/bin/ruby
  Config Dir  /Users/eze/.local/share/mise/installs/ruby/3.4.6/etc
RubyGems      3.7.2
  Gem Home    /Users/eze/.local/share/mise/installs/ruby/3.4.6/lib/ruby/gems/3.4.0
  Gem Path    /Users/eze/.gem/ruby/3.4.0:/Users/eze/.local/share/mise/installs/ruby/3.4.6/lib/ruby/gems/3.4.0
  User Home   /Users/eze
  User Path   /Users/eze/.gem/ruby/3.4.0
  Bin Dir     /Users/eze/.local/share/mise/installs/ruby/3.4.6/bin
Tools         
  Git         2.51.0
  RVM         not installed
  rbenv       not installed
  chruby      not installed
```

## Bundler Build Metadata

```
Timestamp  2025-09-09
Git SHA    b463ced1459
```

## Bundler settings

```
gem.changelog
  Set for the current user (/Users/eze/.bundle/config): false
gem.ci
  Set for the current user (/Users/eze/.bundle/config): false
gem.linter
  Set for the current user (/Users/eze/.bundle/config): "rubocop"
gem.test
  Set for the current user (/Users/eze/.bundle/config): "minitest"
```

## Gemfile

### Gemfile

```ruby
source 'https://rubygems.org'
ruby file: 'mise.toml'

group :development do
  gem 'logger', '~> 1.7', require: false
  gem 'minitest', '~> 5.25', require: false
  gem 'rake', '~> 13.3', require: false
  gem 'rubocop', '~> 1.80', require: false
  gem 'rubocop-minitest', '~> 0.38.2', require: false
  gem 'rubocop-performance', '~> 1.26', require: false
  gem 'rubocop-rake', '~> 0.7.1', require: false
  gem 'simplecov', '~> 0.22.0', require: false
end
```

### Gemfile.lock

```
GEM
  remote: https://rubygems.org/
  specs:
    ast (2.4.3)
    docile (1.4.1)
    json (2.15.0)
    language_server-protocol (3.17.0.5)
    lint_roller (1.1.0)
    logger (1.7.0)
    minitest (5.25.5)
    parallel (1.27.0)
    parser (3.3.9.0)
      ast (~> 2.4.1)
      racc
    prism (1.5.1)
    racc (1.8.1)
    rainbow (3.1.1)
    rake (13.3.0)
    regexp_parser (2.11.3)
    rubocop (1.81.0)
      json (~> 2.3)
      language_server-protocol (~> 3.17.0.2)
      lint_roller (~> 1.1.0)
      parallel (~> 1.10)
      parser (>= 3.3.0.2)
      rainbow (>= 2.2.2, < 4.0)
      regexp_parser (>= 2.9.3, < 3.0)
      rubocop-ast (>= 1.47.1, < 2.0)
      ruby-progressbar (~> 1.7)
      unicode-display_width (>= 2.4.0, < 4.0)
    rubocop-ast (1.47.1)
      parser (>= 3.3.7.2)
      prism (~> 1.4)
    rubocop-minitest (0.38.2)
      lint_roller (~> 1.1)
      rubocop (>= 1.75.0, < 2.0)
      rubocop-ast (>= 1.38.0, < 2.0)
    rubocop-performance (1.26.0)
      lint_roller (~> 1.1)
      rubocop (>= 1.75.0, < 2.0)
      rubocop-ast (>= 1.44.0, < 2.0)
    rubocop-rake (0.7.1)
      lint_roller (~> 1.1)
      rubocop (>= 1.72.1)
    ruby-progressbar (1.13.0)
    simplecov (0.22.0)
      docile (~> 1.1)
      simplecov-html (~> 0.11)
      simplecov_json_formatter (~> 0.1)
    simplecov-html (0.13.2)
    simplecov_json_formatter (0.1.4)
    unicode-display_width (3.2.0)
      unicode-emoji (~> 4.1)
    unicode-emoji (4.1.0)

PLATFORMS
  ruby
  x86_64-darwin-21

DEPENDENCIES
  logger (~> 1.7)
  minitest (~> 5.25)
  rake (~> 13.3)
  rubocop (~> 1.80)
  rubocop-minitest (~> 0.38.2)
  rubocop-performance (~> 1.26)
  rubocop-rake (~> 0.7.1)
  simplecov (~> 0.22.0)

RUBY VERSION
   ruby 3.4.6p54

BUNDLED WITH
   2.7.2