request body model not support for  json deserialize DateTime
```nim
# json serialize DateTime
proc toJsonHook(dt: DateTime, opt = initToJsonOptions()): JsonNode =
  return newJString $dt

# json deserialize DateTime
proc fromJsonHook(dt: var DateTime, jsonNode: JsonNode) =
  dt = parse(jsonNode.getStr, "yyyy-MM-dd'T'HH:mm:sszzz", utc())

model FighterCreate:
  name: string
  skill: string
  createdAt: DateTime
```
```nim
  post "/fighter[fighterCreate:FighterCreate:json]":
    echo "new fighter: ", fighterCreate
```

compile error:
```
/root/.local/share/rtx/installs/nim/2.0.0/lib/pure/json
.nim(1253, 23) Error: type mismatch
Expression: initFromJson(dst.zonedTimeFromTimeImpl,
             getOrDefault(jsonNode, "zonedTimeFromTimeI
mpl"), jsonPath)
  [1] dst.zonedTimeFromTimeImpl: proc (x: Time): ZonedT
ime{.closure, gcsafe.}
  [2] getOrDefault(jsonNode, "zonedTimeFromTimeImpl"): 
JsonNode
  [3] jsonPath: string
```