Fix deprecation warnings

[ggutierrez-sunbright]

There are several warnings involving std::unary_function, std::binary_function and related elements in rDock.

For example:

./include/RbtAtom.h:476:29: warning: 'template<class _Arg, class _Result> struct std::unary_function' is deprecated [-Wdeprecated-declarations]
  476 | class isPiAtom: public std::unary_function<RbtAtom*, RbtBool> {
      |                             ^~~~~~~~~~~~~~
/usr/include/c++/13/bits/stl_function.h:117:12: note: declared here
  117 |     struct unary_function

Those functors should not inherit from any base class, and any predicate derived from them should be a lambda