Fix build on updated EOSIO.CDT
In the "Why was this working before??" category, there did not appear to be any serialization code for StaticVariant on EOSIO, causing builds to fail on updated CDT compilers. Add the serializers so that it now works.
In the "Why was this working before??" category, there did not appear to be any serialization code for StaticVariant on EOSIO, causing builds to fail on updated CDT compilers. Add the serializers so that it now works.