Stop using deprecated macOS API in fsmonitor. * jh/fsmonitor-darwin-modernize: fsmonitor: eliminate call to deprecated FSEventStream function This backport to `maint-2.39` is needed to be able to build on `macos-13`, which we need to update to as we restore the CI health of that branch. Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>