Revert to old shm "last" meaning last row

piker/data/_sharedmem.py

@@ -220,7 +220,7 @@ class ShmArray:
         self,
         length: int = 1,
     ) -> np.ndarray:
-        return self.array[-length]
+        return self.array[-length:]
 
     def push(
         self,

piker/fsp/_volume.py

@@ -135,7 +135,7 @@ async def dolla_vlm(
 
             c, h, l, v = ohlcv.last()[
                 ['close', 'high', 'low', 'volume']
-            ]
+            ][0]
 
             lvlm += price * size
             tina_lvlm = c+h+l/3 * v