Update text of GPL to latest version from FSF

This mostly removes the postal address of the FSF.

This was triggered by rpmlint complaining about
that address being outdated.

Change-Id: Idfe5c615d1109a1038207c1c1b0e0de4da3279f5
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20250803143939.15335-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg32475.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 6325738)

Author: flichtenheld

COPYRIGHT.GPL

@@ -2,7 +2,7 @@
                        Version 2, June 1991
 
  Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
- 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ <https://fsf.org/>
  Everyone is permitted to copy and distribute verbatim copies
  of this license document, but changing it is not allowed.
 
@@ -294,17 +294,17 @@ the "copyright" line and a pointer to where the full notice is found.
     Copyright (C) <year>  <name of author>
 
     This program is free software; you can redistribute it and/or modify
-    it under the terms of the GNU General Public License version 2
-    as published by the Free Software Foundation.
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
 
     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
 
     You should have received a copy of the GNU General Public License along
-    with this program; if not, write to the Free Software Foundation, Inc.,
-    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+    with this program; if not, see <https://www.gnu.org/licenses/>.
 
 Also add information on how to contact you by electronic and paper mail.
 
@@ -328,8 +328,8 @@ necessary.  Here is a sample; alter the names:
   Yoyodyne, Inc., hereby disclaims all copyright interest in the program
   `Gnomovision' (which makes passes at compilers) written by James Hacker.
 
-  <signature of Ty Coon>, 1 April 1989
-  Ty Coon, President of Vice
+  <signature of Moe Ghoul>, 1 April 1989
+  Moe Ghoul, President of Vice
 
 This General Public License does not permit incorporating your program into
 proprietary programs.  If your program is a subroutine library, you may