`Assert::isInstanceOf()` exception message changed in v2.1.3

[PHLAK]

Starting with v2.1.3 the exception message for Assert::isInstanceOf() changed.

For example, the following assertion

use App\Some\Thing;

Assert::isInstanceOf($thing, Thing::class);

would return the following in v2.1.2

Expected an instance of App\Some\Thing. Got: NULL

However, now in v2.1.3 (and v2.1.4) we're getting

Expected an object. Got: NULL

Which isn't as helpful as it used to be.

[shadowhand]

Caused by #346
Refs #348

[shadowhand]

Released in 2.1.5.

[PHLAK]

Thank you!