query.sum() doesn't work

[MihaelIsaev]

I already described that in vapor/fluent-postgres-driver#50

It throws error

[ ERROR ] PostgreSQLError.binaryFloatingPoint: Could not decode Double from binary data type: NUMERIC.

doesn't matter which column type set in the database, I tried with bigint and double precision

[tanner0101]

Fixed and added a test in #72. Thanks for reporting!

let conn = try PostgreSQLConnection.makeTest(transport: .cleartext)
struct Sum: Decodable {
    var sum: Double
}
let rows = try conn.query("SELECT SUM(3.14) as sum", decoding: Sum.self).wait()
switch rows.count {
case 1:
    XCTAssertEqual(rows[0].sum, 3.14)
default: XCTFail("invalid row count")
}