gnu: libsecret: Update to 0.20.4.

* gnu/packages/gnome.scm (libsecret): Update to 0.20.4.

gnu/packages/gnome.scm

@@ -4735,7 +4735,7 @@ (define-public libsoup-minimal
 (define-public libsecret
   (package
     (name "libsecret")
-    (version "0.20.3")
+    (version "0.20.4")
     (source (origin
               (method url-fetch)
               (uri (string-append
@@ -4744,7 +4744,7 @@ (define-public libsecret
                     "libsecret-" version ".tar.xz"))
               (sha256
                (base32
-                "1r4habxdzmn02id324m0m4mg5isf22q1z436bg3vjjmcz1b3rjsg"))))
+                "0a4xnfmraxchd9cq5ai66j12jv2vrgjmaaxz25kl031jvda4qnij"))))
     (build-system gnu-build-system)
     (outputs '("out" "doc"))
     (arguments
@@ -4770,6 +4770,8 @@ (define-public libsecret
     (propagated-inputs
      `(("glib" ,glib))) ; required by libsecret-1.pc
     (inputs
+     ;; The ‘build’ phase complains about missing docbook-xml-4.2 but adding it
+     ;; doesn't seem to affect the build result.
      `(("docbook-xsl" ,docbook-xsl)
        ("libgcrypt" ,libgcrypt)
        ("libxml2" ,libxml2))) ; for XML_CATALOG_FILES