Can't deploy a Middleman project on Github... I don't see the repo

Question

Several days I try to deploy Middleman on Github.

When I want to create a repo to have a personnal URL [website].github.io

I write in the console : middleman deploy

I have this message...

➜  newone git:(master) ✗ middleman deploy
WARN: Unresolved specs during Gem::Specification.reset:
      thor (< 2.0, >= 0.17.0)
      rack (< 3, >= 1.4.5)
      tilt (~> 2.0)
      activesupport (< 5.1, >= 4.2)
      padrino-helpers (~> 0.13.0)
      addressable (~> 2, ~> 2.3)
      listen (~> 3.0.0)
      sass (>= 3.4)
      uglifier (~> 3.0)
      execjs (~> 2.0)
      hashie (~> 3.4)
      concurrent-ruby (~> 1.0)
      backports (~> 3.6)
WARN: Clearing out unresolved specs.
Please report a bug if this causes problems.
/Users/baptiste/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/bundler-1.13.6/lib/bundler/runtime.rb:40:in `block in setup': You have already activated middleman-core 4.2.0, but your Gemfile requires middleman-core 3.3.12. Prepending `bundle exec` to your command may solve this. (Gem::LoadError)
    from /Users/baptiste/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/bundler-1.13.6/lib/bundler/runtime.rb:25:in `map'
    from /Users/baptiste/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/bundler-1.13.6/lib/bundler/runtime.rb:25:in `setup'
    from /Users/baptiste/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/bundler-1.13.6/lib/bundler.rb:99:in `setup'
    from /Users/baptiste/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/bundler-1.13.6/lib/bundler/setup.rb:10:in `<top (required)>'
    from /Users/baptiste/.rbenv/versions/2.2.3/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:119:in `require'
    from /Users/baptiste/.rbenv/versions/2.2.3/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:119:in `require'
    from /Users/baptiste/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/middleman-core-4.2.0/lib/middleman-core/load_paths.rb:34:in `setup_bundler'
    from /Users/baptiste/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/middleman-core-4.2.0/lib/middleman-core/load_paths.rb:15:in `setup_load_paths'
    from /Users/baptiste/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/middleman-cli-4.2.0/bin/middleman:10:in `<top (required)>'
    from /Users/baptiste/.rbenv/versions/2.2.3/bin/middleman:23:in `load'
    from /Users/baptiste/.rbenv/versions/2.2.3/bin/middleman:23:in `<main>'

I really don't know what to do with this error message. Thank you for your help mates.