refactor: add BoundModelBase model property type (#539)

Helps the type checkers to detect mistakes.

Author: jooola

hcloud/core/client.py

@@ -5,6 +5,7 @@
 
 if TYPE_CHECKING:
     from .._client import Client
+    from .domain import BaseDomain
 
 
 class ResourceClientBase:
@@ -72,7 +73,7 @@ def __init__(self, client: Client):
 class BoundModelBase:
     """Bound Model Base"""
 
-    model: Any
+    model: type[BaseDomain]
 
     def __init__(
         self,