Fix: Adjust testUnexpectedSymbolsInput for unfiltered symbols

[shatterproof]

The filtering of provided symbols to useSymbols was removed with commit 914f0da and testUnexpectedSymbolsInput needed to be updated to reflect that in order to prevent random cases of failed tests.

Since a symbol can be any character now after that commit, the test was updated to confirm only symbols from the provided character set are used.

This begs the question though if useSymbols should still at least filter out alphanumeric characters since they are already covered by the other methods useLower, useUpper, and useNumbers?

[valorin]

Ah, nice catch. I forgot about that test, and clearly missed the failing tests.

I think I prefer to keep it completely open. Anything can be considered a symbol.