[C++][Pistache] Fix warnings

[muttleyxd]

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Description of the PR

GCC would complain about two warnings

(...)/api/(...)Api.cpp:24:92: warning: extra ‘;’ [-Wpedantic]
 (...)Api::(...)Api(std::shared_ptr<Pistache::Rest::Router> rtr) { router = rtr; };

(..)/api/(...)Api.cpp: In member function ‘void org::openapitools::server::api::(...)Api::(...)_api_default_handler(const Pistache::Rest::Request&, Pistache::Http::ResponseWriter)’:
(...)/api/(...)Api.cpp:124:69: warning: unused parameter ‘request’ [-Wunused-parameter]
 void (...)Api::(...)_api_default_handler(const Pistache::Rest::Request& request,