Adopted the standard withCString for C strings throughout the library.

Sources/PlaydateKit/JSON/Classes/Encoder.swift

@@ -43,10 +43,10 @@ extension JSON {
 
         /// Call before writing each table value.
         public func addTableMember(name: String) {
-            name.withPlaydateUTF8 { bytes, count in
+            name.withCString { cString in
                 withUnsafeMutablePointer(to: &encoder) {
                     $0.pointee.addTableMember.unsafelyUnwrapped(
-                        $0, bytes.assumingMemoryBound(to: CChar.self), Int32(count))
+                        $0, cString, Int32(name.utf8.count))
                 }
             }
         }
@@ -80,10 +80,10 @@ extension JSON {
 
         /// Writes a string value.
         public func writeString(_ value: String) {
-            value.withPlaydateUTF8 { bytes, count in
+            value.withCString { cString in
                 withUnsafeMutablePointer(to: &encoder) {
                     $0.pointee.writeString.unsafelyUnwrapped(
-                        $0, bytes.assumingMemoryBound(to: CChar.self), Int32(count))
+                        $0, cString, Int32(value.utf8.count))
                 }
             }
         }