feature: add support for Whatsminer M31SV20, and fix a bug with miner factory not identifying the miners properly by removing a V prefix.

docs/miners/supported_types.md

@@ -91,6 +91,7 @@ details {
                 <details>
                     <summary><a href="../whatsminer/M3X/#m31s">M31S</a></summary>
                     <summary><a href="../whatsminer/M3X/#m31sv10">M31SV10</a></summary>
+                    <summary><a href="../whatsminer/M3X/#m31sv20">M31SV20</a></summary>
                     <summary><a href="../whatsminer/M3X/#m31sv60">M31SV60</a></summary>
                     <summary><a href="../whatsminer/M3X/#m31sv70">M31SV70</a></summary>
                 </details>

docs/miners/whatsminer/M3X.md

@@ -122,6 +122,14 @@
         show_root_heading: false
         heading_level: 4
 
+## M31SV20
+
+::: pyasic.miners.whatsminer.btminer.M3X.M31S.BTMinerM31SV20
+    handler: python
+    options:
+        show_root_heading: false
+        heading_level: 4
+
 ## M31SV60
 
 ::: pyasic.miners.whatsminer.btminer.M3X.M31S.BTMinerM31SV60