bpo-30624 remaining bare except (#2108)

bpo-30624 / selectors: use bare 'except' clause instead of 'except
Exception'
diff --git a/Lib/selectors.py b/Lib/selectors.py
index f8b17a1..a9a0801 100644
--- a/Lib/selectors.py
+++ b/Lib/selectors.py
@@ -357,7 +357,7 @@
             poller_events |= self._EVENT_WRITE
         try:
             self._selector.register(key.fd, poller_events)
-        except Exception:
+        except:
             super().unregister(fileobj)
             raise
         return key