Cancelling a query leads to an error message, there is no 'KILL' command in sqlite

[mjpieters]

On keyboard interrupt during a long-running query, an error message is printed:

Encountered error while cancelling query: near "kill": syntax error

That's because litecli tries to treat sqlite like a remote database and sends a kill <connectionid> command, which sqlite doesn't support.

Instead, litecli should call the connection.interrupt() method. No new connection is needed. In main.py:LiteCli.one_iteration(), replace the last KeyboardInterrupt exception handler with:

            except KeyboardInterrupt:
                try:
                    sqlexecute.conn.interrupt()
                except Exception as e:
                    self.echo(
                        "Encountered error while cancelling query: {}".format(e),
                        err=True,
                        fg="red",
                    )
                else:
                    logger.debug("cancelled query")
                    self.echo("cancelled query", err=True, fg="red")

[amjith]

Do you mind making a PR?