Fix Compilation On Xcode 12 Beta 1

Author: danl3v

Sources/SQLite/Typed/Query.swift

@@ -938,7 +938,7 @@ extension Connection {
     private func columnNamesForQuery(_ query: QueryType) throws -> [String: Int] {
         var (columnNames, idx) = ([String: Int](), 0)
         column: for each in query.clauses.select.columns {
-            var names = each.expression.template.split { $0 == "." }.map(String.init)
+            var names = each.expression.template.split(separator: ".")
             let column = names.removeLast()
             let namespace = names.joined(separator: ".")