Allow Symfony 6 (thephpleague#254)

Update composer.json

Update composer.json

Create FUNDING.yml

Merge pull request thephpleague#225 from KenorFR/KenorFR-deprecated-s…

…ymfony

corrects deprecated symfony 5.1

Merge pull request thephpleague#221 from thephpleague/feat-testactual…

…request

Test actual request instead of mock

Update .travis.yml

Merge branch 'master' of github.com:thephpleague/omnipay-common

Allow PHP 5.6 and 7.0 to be installed (thephpleague#182)

* Allow PHP 5.6 and 7.0 to be installed
* Skip listener, use integration
* Remove typehints

Stricter tests