gnu: mg: Update to 20210609.

* gnu/packages/text-editors.scm (mg): Update to 20210609.
[source](snippet): Remove trailing #t.

gnu/packages/text-editors.scm

@@ -506,7 +506,7 @@ (define-public e3
 (define-public mg
   (package
     (name "mg")
-    (version "20180927")
+    (version "20210609")
     (source (origin
               (method git-fetch)
               (uri (git-reference
@@ -515,12 +515,11 @@ (define-public mg
               (file-name (git-file-name name version))
               (sha256
                (base32
-                "14vrm8lvwksf697sqks7xfd1xaqjlqjc9afjk33sksq5p27wr203"))
+                "04c2vqxg31mk15cfrhzrivykis8fmf0m1d8h1qdjdmlfxd4qwaqf"))
               (modules '((guix build utils)))
               (snippet '(begin
                           (substitute* "GNUmakefile"
-                            (("/usr/bin/") ""))
-                          #t))))
+                            (("/usr/bin/") ""))))))
     (build-system gnu-build-system)
     (native-inputs
      `(("pkg-config" ,pkg-config)))