fix: deleted image wrongfully caching

features/serve_uploaded_images.qa.md

@@ -29,7 +29,7 @@ Package: `test` (black-box, new file `test/serve_uploaded_images_test.go`).
    non-empty byte content. For each, `httptest.NewRequest("GET",
    "/static/uploadedImages/"+name, nil)`, no cookie. Assert status `200`;
    `Content-Type` equals the expected value; `Cache-Control` equals
-   `"public, max-age=31536000, immutable"`; `X-Content-Type-Options` equals
+   `"public, no-cache"`; `X-Content-Type-Options` equals
    `"nosniff"`; `Content-Security-Policy` header is absent; body bytes equal
    what was written.
 7. Write a `.svg` file whose content contains an inline `onload` handler