clippy: use chars / byte string literals

Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>

src/backup/datastore.rs

@@ -390,7 +390,7 @@ impl DataStore {
         fn is_hidden(entry: &walkdir::DirEntry) -> bool {
             entry.file_name()
                 .to_str()
-                .map(|s| s.starts_with("."))
+                .map(|s| s.starts_with('.'))
                 .unwrap_or(false)
         }
         let handle_entry_err = |err: walkdir::Error| {