Revert "Remove unneeded boxing"

This boxing is not unneeded, it's actually
required by libusb on MacOS/Linux.

This reverts commit 9f4c4bb.

src/app.rs

@@ -47,7 +47,7 @@ impl App {
 
     pub fn run(self) -> Result<()> {
         display_control::log_current_source();
-        let pnp_detector = PnPDetect::new(&self);
+        let pnp_detector = PnPDetect::new(Box::new(self));
         pnp_detector.detect()?;
 
         Ok(())

src/platform/pnp_detect_windows.rs

@@ -22,14 +22,14 @@ use winapi::um::winuser::{
 /// Detection of plugged in / removed USB devices on Windows: listens for WM_DEVICECHANGE messages.
 /// This code should be removed once libusb supports hotplug notifications on Windows:
 /// https://github.com/libusb/libusb/issues/86
-pub struct PnPDetectWindows<'a> {
+pub struct PnPDetectWindows {
     hwnd: HWND,
-    callback: &'a dyn UsbCallback,
+    callback: Box<dyn UsbCallback>,
     current_devices: HashSet<String>,
 }
 
-impl<'a> PnPDetectWindows<'a> {
-    pub fn new(callback: &'a (dyn UsbCallback + 'a)) -> Self {
+impl PnPDetectWindows {
+    pub fn new(callback: Box<dyn UsbCallback>) -> Self {
         let mut pnp_detect = Self {
             callback,
             current_devices: Self::read_device_list().unwrap_or_default(),