feat: type check alignment format specifiers

Author: jack-tutor

mypy/checkstrformat.py

@@ -1073,6 +1073,14 @@ def conversion_type(
                 return UnionType(
                     [self.named_type("builtins.int"), self.named_type("builtins.str")]
                 )
+        elif p in ["<", ">", "=", "^"]:
+            return UnionType(
+                [
+                    self.named_type("builtins.int"), 
+                    self.named_type("builtins.float"), 
+                    self.named_type("builtins.str")
+                ]
+            )
         else:
             self.msg.unsupported_placeholder(p, context)
             return None