package/readline: fix "Upstream:" tag

The test chckes that the "Upstream:" tag be on the first column, without
any leading character (no space, no bracket of any kind).

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/readline/0002-Readline-8.2-patch-1-fix-crash-when-readline-is-star.patch

@@ -4,8 +4,8 @@ Date: Wed, 5 Oct 2022 10:41:16 -0400
 Subject: [PATCH] Readline-8.2 patch 1: fix crash when readline is started with
  an invalid locale specification
 
-[Upstream: https://git.savannah.gnu.org/cgit/readline.git/patch/?id=7274faabe97ce53d6b464272d7e6ab6c1392837b
- Stripped unrelated ._.gitignore change]
+Upstream: https://git.savannah.gnu.org/cgit/readline.git/patch/?id=7274faabe97ce53d6b464272d7e6ab6c1392837b
+[peter: stripped unrelated ._.gitignore change]
 Signed-off-by: Peter Seiderer <ps.report@gmx.net>
 ---
  nls.c      | 4 ++++