gnu: libportal: Update to 0.4.

* gnu/packages/freedesktop.scm (libportal): Update to 0.4.
[source]: Use the version as commit field.

gnu/packages/freedesktop.scm

@@ -2303,20 +2303,18 @@ fallback to generic Systray support if none of those are available.")
     (license license:lgpl2.1+)))
 
 (define-public libportal
-  (let ((commit "bff3289")
-        (revision "1"))
   (package
     (name "libportal")
-      (version (git-version "0.3" revision commit))
+    (version "0.4")
     (source (origin
               (method git-fetch)
               (uri (git-reference
                     (url "https://github.com/flatpak/libportal")
-                      (commit commit)))
+                    (commit version)))
               (file-name (git-file-name name version))
               (sha256
                (base32
-                  "104b91qircr1i9jkmm6f725awywky52aimrki303kiaadn2v8b5i"))))
+                "1jh6wd96y4i218zbmmqw12zir8p88nm8dlsa3yx3lsqxd5c1krky"))))
     (build-system meson-build-system)
     (arguments
      `(#:phases
@@ -2344,7 +2342,7 @@ fallback to generic Systray support if none of those are available.")
     (synopsis "Flatpak portal library")
     (description
      "libportal provides GIO-style async APIs for most Flatpak portals.")
-      (license license:lgpl2.1+))))
+    (license license:lgpl2.1+)))
 
 (define-public xdg-desktop-portal
   (package