added get_model to get the model of the miner, and reformatted the style of the miner factory getting miner to get a different miner for each type of supported miner

miners/antminer/S9/bmminer.py

@@ -0,0 +1,11 @@
+from miners.bmminer import BMMiner
+
+
+class BMMinerS9(BMMiner):
+    def __init__(self, ip: str) -> None:
+        super().__init__(ip)
+        self.model = "S9"
+        self.api_type = "BMMiner"
+
+    def __repr__(self) -> str:
+        return f"BMMinerS9: {str(self.ip)}"