imaplib: re-raise BaseException instead of bare except

Co-authored-by: Peter Bierma <[email protected]>

Author: foresto

Lib/imaplib.py

@@ -1429,7 +1429,7 @@ def __enter__(self):
             if __debug__ and imap.debug >= 4:
                 prompt = imap.continuation_response
                 imap._mesg(f'idle continuation prompt: {prompt}')
-        except:
+        except BaseException:
             imap._idle_capture = False
             raise