Fix deprecations during test execution and turn deprecation helper back on

[thirsch]

Remaining direct deprecation notices (2)

    2x: shouldNotReceive(), never(), times(0) chaining additional invocation count methods has been deprecated and will throw an exception in a future version of Mockery
        1x in Swift_CharacterStream_ArrayCharacterStreamTest::testByteStreamCanBeImportingUsesValidator
        1x in Swift_CharacterStream_ArrayCharacterStreamTest::testImportingStreamProducesCorrectCharArray

After possibly fixing this, we can revert this commit and turn the deprecation helper back on: 91a4a6b

[thirsch]

Adding 8.2 brought some more warnings. ;-) I'll have a look into this after #4 is done.