BoostJsonAdapter - false negative on isInteger()

[roosterfive]

When a JSON value is constructed from an unsigned, BoostJsonValue#isInteger() returns a false negative as it
tests the value against is_int64() instead of (is_int64() || is_uint64()).

Only see this in unit tests as the tests validate against constructed values whereas values from parsed docs will construct same integer properties as int64_t.

Boost.JSON docs - "When a value is constructed from an unsigned integer, its kind will be kind::uint64. Likewise, a value constructed from a signed integer will have kind::int64." When parsed - "if the number is positive and its value is greater than INT64_MAX, then its type is std::uint64_t. All other numbers are parsed as std::int64_t"