issue: std::string incomplete type in Types.hpp

[aneury1]

Hello it seems this would lead some error in some enviroments when compiling, I was trying on Fedora 38, I compiled successfully in order envs. but not for this so it would be good idea to include it, at the top of the file where should it be.

this is from master branch, I haven't tested in other branchs.

.../capicxx-core-runtime/include/CommonAPI/Types.hpp:113:40: error: return type ‘std::string’ {aka ‘class std::__cxx11::basic_string<char>’} is incomplete
  113 |     virtual std::string getEnv() const {
      |                                        ^