seahorse: fix build with gpgme 2.0+

- add patch from merged upstream MR:
https://gitlab.gnome.org/GNOME/seahorse/-/merge_requests/248
https://gitlab.gnome.org/GNOME/seahorse/-/commit/aa68522cc696fa491ccfdff735b77bcf113168d0

Upstream issue:
https://gitlab.gnome.org/GNOME/seahorse/-/issues/410

Fixes build failure:
```
../pgp/seahorse-gpgme.c: In function 'on_gpgme_event':
../pgp/seahorse-gpgme.c:487:14: error: 'GPGME_EVENT_NEXT_TRUSTITEM'
undeclared (first use in this function);
did you mean 'GPGME_EVENT_NEXT_KEY'?
  487 |         case GPGME_EVENT_NEXT_TRUSTITEM:
      |              ^~~~~~~~~~~~~~~~~~~~~~~~~~
      |              GPGME_EVENT_NEXT_KEY
...
ninja: build stopped: subcommand failed.
```

pkgs/by-name/se/seahorse/package.nix

@@ -2,6 +2,7 @@
   stdenv,
   lib,
   fetchurl,
+  fetchpatch,
   vala,
   meson,
   ninja,
@@ -37,6 +38,16 @@ stdenv.mkDerivation rec {
     hash = "sha256-nBkX5KYff+u3h4Sc42znF/znBsNGiAuZHQVtVNrbysw=";
   };
 
+  patches = [
+    # Fix build with gpgme 2.0+
+    # https://gitlab.gnome.org/GNOME/seahorse/-/merge_requests/248
+    (fetchpatch {
+      name = "seahorse-allow-build-with-gpgme-2_0.patch";
+      url = "https://gitlab.gnome.org/GNOME/seahorse/-/commit/aa68522cc696fa491ccfdff735b77bcf113168d0.patch";
+      hash = "sha256-xd5K8xUGuMk+41JROsq7QpZ5gD2jPAbv1kQdLI3z9lc=";
+    })
+  ];
+
   nativeBuildInputs = [
     meson
     ninja