!lowercase-string does not mean the string is upper case, Assert::upper

[zerkms]

Assert::upper is typed as !lowercase-string, while "not all lowercase" means not only "all upper case" but also "is mixed case".

'fOo' is !lowecase-string, yet it's not all upper case.

I reported a request for uppercase-string psalm type, but meanwhile we should remove the wrong typing.

References:

• Feature request: uppercase-string vimeo/psalm#3222

[zerkms]

And in fact, while implementing tests for #126 I have found that at the moment @psalm-assert !lowercase-string $value annotation does not add anything: it's basically unusable given !lowercase-string is only a valid assertion type, but not a valid data type.