♲ Stop handling EINTR around time.sleep()

`IOError` is an alias of `OSError` since Python 3.3. Python 3 also
indroduced a new exception `InterruptedError` which represents
`EINTR`. The `time.sleep()` call could raise

    IOError: [Errno 4] Interrupted function call

on KBInt under Python 2, which would be `InterruptedError` under
Python 3 but it's not raised anymore post PEP 475 that was implemented
in Python 3.5. So it does not actually need to be handled in modern
runtimes.

Refs:
* https://stackoverflow.com/a/52613818/595220
* https://peps.python.org/pep-0475/
* python/cpython#56671
* https://stackoverflow.com/a/38258781/595220
* https://docs.python.org/3/library/exceptions.html#InterruptedError
* python/cpython#36893

cheroot/server.py

@@ -1729,9 +1729,7 @@ def safe_start(self):
         """Run the server forever, and stop it cleanly on exit."""
         try:
             self.start()
-        except (KeyboardInterrupt, IOError):
-            # The time.sleep call might raise
-            # "IOError: [Errno 4] Interrupted function call" on KBInt.
+        except KeyboardInterrupt:
             self.error_log('Keyboard Interrupt: shutting down')
             self.stop()
             raise