chore(deps): bump keytap 0.2 → 0.4 for macOS modifier-events fix

0.2 read CGEventFlags via CGEventGetIntegerValueField(event, 0x81),
which is not a valid CGEventField id — macOS silently returned 0, so
FlagsChanged events produced no KeyDown / KeyUp for any modifier key
and the PTT / toggle chords never armed on macOS. 0.4 uses the
documented CGEventGetFlags(event) API.

0.3 (tracing / serde / Fn / IntlBackslash) is picked up as a free
consequence; no API surface we depend on changed.

tauri/src-tauri/Cargo.lock

@@ -1878,9 +1878,9 @@ dependencies = [
 
 [[package]]
 name = "keytap"
-version = "0.2.0"
+version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b1c93022d3131914f823f2efa2a2991ce45383df1649255c9803e7cb98209918"
+checksum = "e84f1ed19a610883f09c7dfd6d70962f26812b09f801648e34bb1a4111d26ab6"
 dependencies = [
  "crossbeam-channel",
  "evdev",

tauri/src-tauri/Cargo.toml

@@ -60,7 +60,7 @@ tauri-plugin-process = "2.0"
 # surface, clean shutdown via Drop, no `set_is_main_thread(false)`
 # dance required (the Sonoma-crashing layout-translation path simply
 # isn't called).
-keytap = "0.2"
+keytap = "0.4"
 
 [features]
 # This feature is used for production builds or when `devPath` points to the filesystem