Fix forex snapshot last_quote ask/bid prices

TickerSnapshot.last_quote reuses the stock LastQuote model, which reads
ask/bid prices from P/p. Forex snapshot quotes send a/b instead, so
get_snapshot_ticker/all/direction for forex returned ask_price and
bid_price as None. Fall back to a/b when P/p are absent.

Author: justinpolygon

massive/rest/models/quotes.py

@@ -52,12 +52,13 @@ def from_dict(d):
             sequence_number=d.get("q", None),
             sip_timestamp=d.get("t", None),
             participant_timestamp=d.get("y", None),
-            ask_price=d.get("P", None),
+            # stocks send P/p; forex snapshot quotes send a/b
+            ask_price=d.get("P", d.get("a")),
             ask_size=d.get("S", None),
             ask_exchange=d.get("X", None),
             conditions=d.get("c", None),
             indicators=d.get("i", None),
-            bid_price=d.get("p", None),
+            bid_price=d.get("p", d.get("b")),
             bid_size=d.get("s", None),
             bid_exchange=d.get("x", None),
             tape=d.get("z", None),