[gtk-mac-integration] Update AM_GNU_GETTEXT_VERSION to match gtk-osx installed gettext.

[John Ralls <jralls src gnome org>]

commit 6674d0bb0e7b617a473f8a7fe3cb4c2540b346e7
Author: John Ralls <jralls ceridwen us>
Date:   Fri Aug 14 14:27:02 2020 -0700

    Update AM_GNU_GETTEXT_VERSION to match gtk-osx installed gettext.

 configure.ac | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/configure.ac b/configure.ac
index 8fa3e32..2e240de 100644
--- a/configure.ac
+++ b/configure.ac
@@ -41,7 +41,7 @@ dnl ================================================================
 dnl Gettext stuff.
 dnl ================================================================
 AM_GNU_GETTEXT([external])
-AM_GNU_GETTEXT_VERSION([0.19.8])
+AM_GNU_GETTEXT_VERSION([0.20.2])
 
 AC_SUBST([GETTEXT_PACKAGE], [gtk-mac-integration])
 AC_DEFINE_UNQUOTED([GETTEXT_PACKAGE], "$GETTEXT_PACKAGE", [Define to the gettext package name.])