Fix Travis-CI scripts always passing

[IonBazan]

Q	A
Bug fix?	yes
New feature?	no
Doc updated	no
BC breaks?	no
Deprecations?	no
Tests pass?	no
License	MIT

Currently the tests are always marked as passed on Travis-CI due to lack of set -ex on the beginning of the tests script.
This is probably why we missed the failing tests introduced in 8ec6bea with Doctrine ORM < 2.5 when Embeddable has been introduced.

• Skip testing Embeddable entities on Doctrine ORM <2.5
• Bump PHPUnit minimum version to 7.5 which introduced assertIsCallable()
• Skip loading BlogPostSeo and BlogPostWithEmbedded metadata in JMS\Serializer\Tests\Serializer\Doctrine\ObjectConstructorTest

[goetas]

If is too difficult, why not just dropping doctrine <2.5 support?

[IonBazan]

@goetas I fixed it by moving the Article, BlogPost and Comment entities to a separate directory and loading only the specific metadata in ObjectConstructorTest .

[goetas]

Great!

[goetas]

Thanks!