Coerce IPC `addr` to `tuple` in `.delete_addr()`

`msgpack` deserializes tuples as lists over IPC so
the `bidict.inverse.pop()` needs a `tuple`-cast to
match registry keys.

Regressed-by: 85457cb (`registry_addrs` change)
Found-via: `/run-tests` test_stale_entry_is_deleted

(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code

tractor/_runtime.py

@@ -2044,8 +2044,11 @@ class Arbiter(Actor):
         self,
         addr: tuple[str, int|str],
     ) -> tuple[str, str]|None:
+        # NOTE: `addr` arrives as a `list` over IPC
+        # (msgpack deserializes tuples -> lists) so
+        # coerce to `tuple` for the bidict hash lookup.
         uid: tuple | None = self._registry.inverse.pop(
-            addr,
+            tuple(addr),
             None,
         )
         if uid: