refactor: construct filepaths more idiomatically

src/download.rs

@@ -37,8 +37,7 @@ pub async fn download(
 ) -> Result<HttpResponse, Error> {
     let id = req.match_info().query("id");
     let (file_id, file_name, valid_till, content_type, delete) = load_file_info(id, &db).await?;
-    let mut path = config.files_dir.clone();
-    path.push(&file_id);
+    let path = config.files_dir.join(&file_id);
 
     let mime = Mime::from_str(&content_type).unwrap_or(APPLICATION_OCTET_STREAM);
     let mut response = match get_view_type(&req, &mime, &path, delete).await {

src/upload.rs

@@ -103,8 +103,7 @@ async fn create_unique_file(
 ) -> Result<(String, PathBuf), std::io::Error> {
     loop {
         let file_id = gen_file_id();
-        let mut file_path = config.files_dir.clone();
-        file_path.push(&file_id);
+        let file_path = config.files_dir.join(&file_id);
         match OpenOptions::new()
             .write(true)
             .create_new(true)