Don't export "hum" date versions for trade objects.

They are not used and have a rather high performance penalty due to
using arrow.get

freqtrade/rpc/api_server/api_schemas.py

@@ -151,13 +151,11 @@ class TradeSchema(BaseModel):
     fee_close: Optional[float]
     fee_close_cost: Optional[float]
     fee_close_currency: Optional[str]
-    open_date_hum: str
     open_date: str
     open_timestamp: int
     open_rate: float
     open_rate_requested: Optional[float]
     open_trade_value: float
-    close_date_hum: Optional[str]
     close_date: Optional[str]
     close_timestamp: Optional[int]
     close_rate: Optional[float]

freqtrade/rpc/telegram.py

@@ -294,6 +294,7 @@ class Telegram(RPCHandler):
 
             messages = []
             for r in results:
+                r['open_date_hum'] = arrow.get(r['open_date']).humanize()
                 lines = [
                     "*Trade ID:* `{trade_id}` `(since {open_date_hum})`",
                     "*Current Pair:* {pair}",