Fix debian InRelease Acquire-By-Hash newline (#29204)

There is a missing newline when generating the debian apt repo InRelease
file, which results in output like:

```
[...]
Date: Wed, 14 Feb 2024 05:03:01 UTC
Acquire-By-Hash: yesMD5Sum:
 51a518dbddcd569ac3e0cebf330c800a 3018 main-dev/binary-amd64/Packages
[...]
```

It appears this would probably result in apt ignoring the
Acquire-By-Hash setting and not using the by-hash functionality,
although I'm not sure how to confirm it.

services/packages/debian/repository.go

@@ -342,7 +342,7 @@ func buildReleaseFiles(ctx context.Context, ownerID int64, repoVersion *packages
 	fmt.Fprintf(w, "Components: %s\n", strings.Join(components, " "))
 	fmt.Fprintf(w, "Architectures: %s\n", strings.Join(architectures, " "))
 	fmt.Fprintf(w, "Date: %s\n", time.Now().UTC().Format(time.RFC1123))
-	fmt.Fprint(w, "Acquire-By-Hash: yes")
+	fmt.Fprint(w, "Acquire-By-Hash: yes\n")
 
 	pfds, err := packages_model.GetPackageFileDescriptors(ctx, pfs)
 	if err != nil {