remove flawfinder from ci

Flawfinder is a simple tool that lexically find possible security flaws. Due to this there are many instances in which flawfinder will report a false positive, e.g. a struct with a member called access will report a warning about the function access: int access(const char *pathname, int mode);. The tool is still useful as a general addition as there are cases in which it is correct but it shouldn't be in run in ci (or at least not by default)