refactor(ffi): replace implicit drop in cffi with explicit drop(Arc::from_raw(var)) (#7664)

for improved clarity and consistency with existing code.

deltachat-ffi/src/lib.rs

@@ -4773,7 +4773,7 @@ pub unsafe extern "C" fn dc_accounts_unref(accounts: *const dc_accounts_t) {
         eprintln!("ignoring careless call to dc_accounts_unref()");
         return;
     }
-    let _ = Arc::from_raw(accounts);
+    drop(Arc::from_raw(accounts));
 }
 
 #[no_mangle]