fix knft for py3.10 (#2722)

* fix knft for py3.10

pwndbg/aglib/kernel/nftables.py

@@ -117,7 +117,8 @@ class Expr:
 
     def print(self, print_nested: bool = True):
         expr_name = self.expr_name
-        print(f'{expr_name} @ 0x{int(self._addr['data'].address):x}')
+        addr = int(self._addr["data"].address)
+        print(f"{expr_name} @ 0x{addr:x}")
 
         if not print_nested:
             return