Change license from GPL-2.0-or-later to GPL-3.0-or-later

I just realized I can use GPL-3.0-or-later. I prefer GPL-3.0-or-later
over GPL-2.0-or-later. And libssh's LGPL-2.1-or-later, plplot's
LGPL-2.0-or-later, and gtk's LGPL-2.1-or-later licenses are compatible
with GPL-3.0-or-later.

1 files changed, 1 insertions, 1 deletions

diff --git a/README.md b/README.md
index bef9e87..5680de5 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 work in progress
 
-The software is licensed under GPL-2.0-or-later. But list.c and list.h contain source code I edited from book "C Primer Plus" Chapter17 practice problem 2 which contain codes from its example codes, and the author of "C Primer Plus" does not have a license for list.c and list.h, so the author of "C Primer Plus" has the copyright on list.c and list.h, so list.c and list.h can be considered non-free close souce proprietary code.
+The software is licensed under GPL-3.0-or-later. But list.c and list.h contain source code I edited from book "C Primer Plus" Chapter17 practice problem 2 which contain codes from its example codes, and the author of "C Primer Plus" does not have a license for list.c and list.h, so the author of "C Primer Plus" has the copyright on list.c and list.h, so list.c and list.h can be considered non-free close souce proprietary code.
 
 Read local and remote decoded CAN messages I want, append to a file, plot to a GUI with some controls. Use it with [mycan](https://git.flylightning.xyz/mycan/).