nixos/paperless: Always buidl tesseract with english

With the changes introduced in #303388 tesseract would only be compiled
with the languages defined in `PAPERLESS_OCR_LANGUAGE`. However, english
is always required, making tesseract fail to build when only non-english
languages are defined in tesseract:

```
eng.traineddata must be present in tessdata for Tesseract to work
```

1 files changed, 4 insertions, 1 deletions

diff --git a/nixos/modules/services/misc/paperless.nix b/nixos/modules/services/misc/paperless.nix
index 3456098073b34..e564fe3b8317b 100644
--- a/nixos/modules/services/misc/paperless.nix
+++ b/nixos/modules/services/misc/paperless.nix
@@ -203,9 +203,12 @@ in
       apply = pkg: pkg.override {
         tesseract5 = pkg.tesseract5.override {
           # always enable detection modules
+          # tesseract fails to build when eng is not present
           enableLanguages = if cfg.settings ? PAPERLESS_OCR_LANGUAGE then
-            [ "equ" "osd" ]
+            lists.unique (
+              [ "equ" "osd" "eng" ]
               ++ lib.splitString "+" cfg.settings.PAPERLESS_OCR_LANGUAGE
+            )
           else null;
         };
       };