Drop support for Emacs 24.3

Emacs 24.3 was released in March of 2013.  Emacs 24.4 was released in
October of 2014.  emacs-buttercup tries to support as old Emacsen as
possible as it is a tool that can reasonably be expected to be used on
old Emacsen during testing of other packages.  But there must be a
limit.  Emacs 24.3 is 10.5 years old at this point, and all remotely
recent distributions come with newer versions of Emacs.

.github/workflows/test.yml

@@ -34,7 +34,6 @@ jobs:
     strategy:
       matrix:
         emacs_version:
-          - 24.3
           - 24.4
           - 24.5
           - 25.1

buttercup.el

@@ -6,7 +6,7 @@
 ;; Version: 1.32
 ;; Author: Jorgen Schaefer <[email protected]>
 ;; Maintainer: Ola Nilsson <[email protected]>
-;; Package-Requires: ((emacs "24.3"))
+;; Package-Requires: ((emacs "24.4"))
 ;; URL: https://github.com/jorgenschaefer/emacs-buttercup
 
 ;; This program is free software; you can redistribute it and/or

tests/test-buttercup.el

@@ -121,8 +121,8 @@ text properties using `ansi-color-apply'."
     (with-current-buffer buffer
       (let ((tab-width 8)          ; terminal uses 8 char tabs
             (indent-tabs-mode nil) ; make sure move-* does not insert tabs
-            ;; default tab-stops (8 char interval)  Can be nil from 24.4 forward...
-            (tab-stop-list (eval (car (get 'tab-stop-list 'standard-value))))
+            ;; default tab-stops (8 char interval)
+            tab-stop-list
             ctrl-char)
         (save-match-data
           (while (string-match "\\(.*?\\)\\([\b\t\n\v\f\r]\\)\\([^z-a]*\\)" string)