Enable clang-tidy readability-container-size-empty check

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

.clang-tidy

@@ -1,7 +1,6 @@
 Checks:
   -*,
   readability-*,
-  -readability-container-size-empty,
   -readability-else-after-return,
   -readability-implicit-bool-conversion,
   -readability-function-cognitive-complexity,

include/argparse/argparse.hpp

@@ -525,7 +525,7 @@ public:
             stream << mNames[0] << ": required.";
             throw std::runtime_error(stream.str());
           }
-          if (mIsUsed && mIsRequired && mValues.size() == 0) {
+          if (mIsUsed && mIsRequired && mValues.empty()) {
             std::stringstream stream;
             stream << mUsedName << ": no value provided.";
             throw std::runtime_error(stream.str());