Fix build on OpenBSD (and probably other BSDs too)

notify-5.0.0-pre.14 does not build on these systems; this was fixed in
notify-rs/notify@41a74f0 , which landed in pre.15.

Author: umanwizard

Cargo.lock

@@ -14,7 +14,7 @@ tracing = "0.1.32"
 jod-thread = "0.1.2"
 walkdir = "2.3.2"
 crossbeam-channel = "0.5.4"
-notify = "=5.0.0-pre.14"
+notify = "=5.0.0-pre.15"
 
 vfs = { path = "../vfs", version = "0.0.0" }
 paths = { path = "../paths", version = "0.0.0" }