Check only for file sizes of 0 and 4096

[ci skip]

https://community.openproject.com/wp/30450

frontend/src/app/modules/attachments/attachments-upload/attachments-upload.component.ts

@@ -156,8 +156,8 @@ export class AttachmentsUploadComponent implements OnInit {
       }
 
       // Files however MAY have no mime type as well
-      // so fall back to checking zero or multitudes of 4096:
+      // so fall back to checking zero or 4096 bytes
-      if ((file.size % 4096) === 0) {
+      if (file.size === 0 || file.size === 4096) {
         console.warn(`Skipping file because of file size (${file.size}) %O`, file);
         return false;
       }