[CodeQuality] Skip dynamic second arg or has uppercase second arg on SimplifyStrposLowerRector

[samsonasik]

Fixes rectorphp/rector#8618

[samsonasik]

@kkmuffme this should fix rectorphp/rector#8618

[samsonasik]

All checks have passed 🎉 @TomasVotruba I am merging it ;)

[kkmuffme]

@samsonasik thanks, but I'm not sure that's a good fix.
https://getrector.com/demo/27617834-bf9d-4730-881d-af84e759161b is only lowercase, so this should be changed according to what you said?

Also what if the uppercase letters are non-latin A-Z, e.g. cyrillic then this fix still has the same bug as before I guess?

[samsonasik]

direct string is safer for this, if you mean non-latin got unicode, that still correct, as strtolower only transform non-unicode to lower, so comparison will still correct.