[FIX] Add names to middlewares

[Neirda24]

• [x] Bug fix
• [ ] New feature
• [ ] BC breaks
• [ ] Deprecations
• [ ] Tests pass

Fixed tickets: [comma-separated list of tickets fixed by the PR, if any] License: MIT

Allow the use of HandlerStack::before($name,...) and HandlerStack::after($name,...)

[florianpreusner]

Nice, thanks for your effort, @Neirda24!

[florianpreusner]

Released in v7.1.1 (https://github.com/8p/EightPointsGuzzleBundle/releases/tag/v7.1.1)