Update composer.json

[mvar]

Fixed incorrect version requirement.

Q	A
Bug fix?	yes
New feature?	no
BC breaks?	no
Deprecations?	no
Tests pass?	yes
Fixed tickets
License	MIT
Doc PR

[sstok]

This shouldn't make a difference as a space equals a ,
https://getcomposer.org/doc/articles/versions.md#range

[mvar]

Thanks for information @sstok

I thought this could be a problem because installing api-platform/core with minimum-stability: dev was failing:

$ composer require api-platform/core
Using version ^2.1@dev for api-platform/core                                    
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)                                   
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for api-platform/core ^2.1@dev -> satisfiable by api-platform/core[2.1.x-dev].
    - Conclusion: remove willdurand/negotiation 2.x-dev
    - Conclusion: don't install willdurand/negotiation 2.x-dev
    - api-platform/core 2.1.x-dev requires willdurand/negotiation ^2.0.3 <2.3 -> satisfiable by willdurand/negotiation[v2.0.3, v2.1.0, v2.2.0, v2.2.1].
    - Can only install one of: willdurand/negotiation[v2.0.3, 2.x-dev].
    - Can only install one of: willdurand/negotiation[v2.1.0, 2.x-dev].
    - Can only install one of: willdurand/negotiation[v2.2.0, 2.x-dev].
    - Can only install one of: willdurand/negotiation[v2.2.1, 2.x-dev].
    - Installation request for willdurand/negotiation (locked at 2.x-dev) -> satisfiable by willdurand/negotiation[2.x-dev].


Installation failed, reverting ./composer.json to its original content.

Later I set api-platform/core and willdurand/negotiation to stable versions and it works.

[dunglas]

See #1104 and willdurand/Negotiation#94.