(138138207) JSONEncoder using large amount of memory when encoding array of structs (#1039)

Co-authored-by: Kevin Perry <kperry@apple.com>

Author: jmschonfeld

Sources/FoundationEssentials/JSON/JSONEncoder.swift

@@ -589,7 +589,7 @@ enum JSONFuture {
         var dict: [String: JSONFuture] = [:]
 
         init() {
-            self.dict.reserveCapacity(20)
+            self.dict.reserveCapacity(4)
         }
 
         init(dict: [String: JSONFuture]) {