Remove syntaxCheck attribute

[Xartrick]

When running unit tests, a warning is displayed :

λ  soundcloud master ✗ phpunit --bootstrap vendor/autoload.php                
PHPUnit 7.2.4 by Sebastian Bergmann and contributors.

  Warning - The configuration file did not pass validation!
  The following problems have been detected:

  Line 11:
  - Element 'phpunit', attribute 'syntaxCheck': The attribute 'syntaxCheck' is not allowed.

  Test results may not be as expected.

[...]

Solution is to completely remove this attribute.

[njasm]

@Xartrick - that is probably true with phpunit >= 7.x.x but our composer.json still requires a lower version. can you try to upgrade phpunit in the composer level and see if everything still works? if so... we'll remove that attribute from config, and start requiring a phpunit that works with 7.0 and above.

also, we need upgrade the README to support only 7.0 or above if we go that route.

"phpunit/phpunit": "5.7.*"

[Xartrick]

Testing multiple PHPUnit versions didn't introduce any issue.

"phpunit/phpunit": "7.0.0"

PHPUnit 7.0.0 by Sebastian Bergmann and contributors.

................................................................. 65 / 65 (100%)


Time: 632 ms, Memory: 6.00MB

OK (65 tests, 106 assertions)

"phpunit/phpunit": ">=7.0.0"

PHPUnit 7.4-g39a268b85 by Sebastian Bergmann and contributors.

................................................................. 65 / 65 (100%)


Time: 657 ms, Memory: 6.00MB

OK (65 tests, 106 assertions)

"phpunit/phpunit": "7.2.4"

PHPUnit 7.2.4 by Sebastian Bergmann and contributors.

................................................................. 65 / 65 (100%)


Time: 928 ms, Memory: 12.00MB

OK (65 tests, 106 assertions)