tree-wide: use 'dyn' for all trait objects

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

src/backup/dynamic_index.rs

@@ -180,7 +180,7 @@ impl DynamicIndexReader {
         Ok(())
     }
 
-    pub fn dump_pxar(&self, mut writer: Box<Write>) -> Result<(), Error> {
+    pub fn dump_pxar(&self, mut writer: Box<dyn Write>) -> Result<(), Error> {
 
         let mut buffer = Vec::with_capacity(1024*1024);