Update required PHP version to meet actual requirements.

[chesio]

Fixes #58.

[mdaskalov]

Thx chesio.
Do you think it will work with 5.4? The travis build file includes 5.4, 5.6 and 7.0 and the build goes trough.

[chesio]

I guess the build passes, because test suite currently does not cover \Mpay24\Mpay24Confirmation class, where the PHP 5.6+ constructs are present. Try adding some tests for this class and see what happens.

[stefanpolzer]

@mdaskalov why you want to maintain unsupported PHP versions? PHP 5.6 and and 7.0 are EOL since last Month. PHP 5.5 is EOL since 2016 and PHP 5.4 since 2015 I guess. If someone still uses PHP 5.4, I assume he will also not update the mpay24-php package. On the other hand, if someone staring a new Project it will properly be with PHP 7.2 or PHP 7.3, right? The new versions also have no big benefit from a functional point of view. So if someone is using an older package of mpay24-php there is no disadvantaged because all features that someone uses are continue to working. From a security point of view: with older PHP versions there are quite a lot issues. Because this is a package that is related to Money transaction it would be a wise signal to say: "We care about security, therefore we do not support older PHP versions, but if you have to use a older PHP version you sill can use an older version that have all (or almost all) features included", or did I miss something that prevents you from stopping the support for PHP 5.5 or older?

[zirnipa]

@mdaskalov Please set the requirements to php >= 7.2

[TheLevti]

At minimum 7.1

Everything below reached end of life. Also with 7.1+ we can have all the nice things php currently offers (type hints, ...).

I would also suggest 7.2.

[stefanpolzer]

@zirnipa can you close this PR? A similar code is in the merged PR #90