Enable clang-tidy cppcoreguidelines-special-member-functions check

Also adds a default destructor, as recommended by the check.

Signed-off-by: Sean Robinson <sean.robinson@scottsdalecc.edu>

.clang-tidy

@@ -1,5 +1,6 @@
 Checks:
   -*,
+  cppcoreguidelines-special-member-functions,
   readability-*,
   -readability-else-after-return,
   -readability-function-cognitive-complexity,

include/argparse/argparse.hpp

@@ -910,6 +910,8 @@ public:
     }
   }
 
+  ~ArgumentParser() = default;
+
   ArgumentParser &operator=(const ArgumentParser &other) {
     auto tmp = other;
     std::swap(*this, tmp);