Fix Parquet multi column byte writing (Bears-R-Us#3312)

For Parquet, we were previously incorrectly writing
byte columns for segmented array values by setting reptition
level to "required", when it should have been "optional". By
fixing that schema setup, we will correctly write the definition
level of each value.

src/ArrowFunctions.cpp

@@ -952,7 +952,7 @@ std::shared_ptr<parquet::schema::GroupNode> SetupSchema(void* column_names, void
         auto list = parquet::schema::GroupNode::Make("list", parquet::Repetition::REPEATED, {element});
         fields.push_back(parquet::schema::GroupNode::Make(cname_ptr[i], parquet::Repetition::OPTIONAL, {list}, parquet::ConvertedType::LIST));
       } else {
-        fields.push_back(parquet::schema::PrimitiveNode::Make(cname_ptr[i], parquet::Repetition::REQUIRED, parquet::Type::BYTE_ARRAY, parquet::ConvertedType::NONE));
+        fields.push_back(parquet::schema::PrimitiveNode::Make(cname_ptr[i], parquet::Repetition::OPTIONAL, parquet::Type::BYTE_ARRAY, parquet::ConvertedType::NONE));
       }
     }
   }