Support PHP 7.2

[amcsi]

Starting with a .travis.yml file change to see what doesn't work.

[amcsi]

@weierophinney There are failures (only for lowest dependencies) because of a deprecation in zend-validator:

1) ZendTest\Uri\MailtoTest::testInvalidMailtoUris with data set #2 ('mailto:[email protected]/bar/baz')
idn_to_utf8(): INTL_IDNA_VARIANT_2003 is deprecated
/home/travis/build/zendframework/zend-uri/vendor/zendframework/zend-validator/src/EmailAddress.php:545
/home/travis/build/zendframework/zend-uri/vendor/zendframework/zend-validator/src/EmailAddress.php:494
/home/travis/build/zendframework/zend-uri/src/Mailto.php:54
/home/travis/build/zendframework/zend-uri/test/MailtoTest.php:157

Are deprecation warnings acceptable for lowest dependencies?
Otherwise probably the minimal dependency that introduces the fix to this deprecation (if intl is loaded) is in zend-validator 2.10.2: zendframework/zend-validator@010084d

[weierophinney]

In this case, bump the minimum supported version of zend-validator as part of the patch; that's essentially what is necessary to make this component work under 7.2.

Thanks!

[amcsi]

@weierophinney I tried 2.10.1 which is one version lower than I anticipated, and it passes there for lowest.
I'm going to investigate to see which is truly the earliest good version.

By the way this tests pass for the current lowest (2.5.0) if the intl extension is not loaded. Apparently the iffy behavior actually starts happening once the intl extension is enabled.

[amcsi]

Seems like ^2.10 is enough. zendframework/zend-validator#175, https://github.com/zendframework/zend-validator/releases/tag/release-2.10.0

[amcsi]

I've generated the composer.lock file by removing vendor and composer.lock and doing composer install --ignore-platform-reqs

[weierophinney]

Thanks, @amcsi !