Support PHP 7.4 in acceptance test infrastructure

[phil-davis]

The Behat acceptance test infrastructure runs separately to the system-under-test. Nowadays it gets used for running acceptance tests against other backends as well as the regular ownCloud10.

Update the dependencies for the Behat acceptance test infrastructure so it will support PHP 7.4

See issue #36509 for the other task - to support PHP 7.4 for the ownCloud10 server.

Things to check when doing this:

• tests work fine in drone against ownCloud10
• tests run fine locally when using just a PHP dev server and running the test infrastructure out of the same clone of the repo
• tests run fine locally when the git-clone-under-test is running with an Apache web server user www-data

[phil-davis]

Note: https://drone.owncloud.com/owncloud/core/23222/4/4

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - sensiolabs/behat-page-object-extension v2.3.0 requires php >=7.1.3,<7.4 -> your PHP version (7.4.1) does not satisfy that requirement.
    - sensiolabs/behat-page-object-extension v2.3.1 conflicts with guzzlehttp/guzzle[5.3.0].
    - sensiolabs/behat-page-object-extension v2.3.1 conflicts with guzzlehttp/guzzle[5.3.1].
    - sensiolabs/behat-page-object-extension v2.3.1 conflicts with guzzlehttp/guzzle[5.3.2].
    - sensiolabs/behat-page-object-extension v2.3.1 conflicts with guzzlehttp/guzzle[5.3.3].
    - sensiolabs/behat-page-object-extension v2.3.1 conflicts with guzzlehttp/guzzle[5.3.4].
    - Installation request for sensiolabs/behat-page-object-extension ^2.3 -> satisfiable by sensiolabs/behat-page-object-extension[v2.3.0, v2.3.1].
    - Installation request for guzzlehttp/guzzle ^5.3 -> satisfiable by guzzlehttp/guzzle[5.3.0, 5.3.1, 5.3.2, 5.3.3, 5.3.4].

make: *** [vendor-bin/behat/vendor] Error 2
Makefile:402: recipe for target 'vendor-bin/behat/vendor' failed

This is the primary reason for this issue.

https://github.com/sensiolabs/BehatPageObjectExtension/pull/128/files brought support for PHP 7.4

behat-page-object-extension 2.3.0 required "php": ">=7.1.3,<7.4" in composer.json
For 2.3.1 that changes to "php": "^7.2" - so that drops PHP 7.1. That will be OK - we will not be able to run acceptance tests (easily) on PHP 7.1. We will drop PHP 7.1 support "soon" anyway.

But it also added a "conflict" section: "guzzlehttp/guzzle": "<6.3"

That means there is no way to use the combination of PHP 7.4, guzzle 5.* and behat-page-object-extension (neither 2.3.0 or 2.3.1 work in that combination).

So we are forced to go to Guzzle6 to be able to even try to run Behat acceptance tests with PHP 7.4