Update minimum support version

Emacs 29.1 was released so that we drop 26.x support

.github/workflows/test.yml

@@ -10,9 +10,9 @@ jobs:
     strategy:
       matrix:
         emacs_version:
-          - 26.1
           - 27.2
           - 28.2
+          - 29.1
           - snapshot
     steps:
     - uses: purcell/setup-emacs@master

CHANGES.md

@@ -3,7 +3,7 @@
 *Under development*
 
 *   **Breaking changes:**
-    - GNU Emacs 26.1 or later is required.
+    - GNU Emacs 27.1 or later is required.
     - Don't allow space between label and text in reference link same as CommonMark [GH-774][]
     - Whitespace is required before the closing sequence of an atx header. [GH-778][]
 

README.md

@@ -1086,7 +1086,7 @@ contributions!  See the [contributors graph][contrib] for details.
 ## Bugs
 
 markdown-mode is developed and tested primarily for compatibility
-with GNU Emacs 26.1 and later.  If you find any bugs in
+with GNU Emacs 27.1 and later.  If you find any bugs in
 markdown-mode, please construct a test case or a patch and open a
 ticket on the [GitHub issue tracker][issues].  See the
 contributing guidelines in `CONTRIBUTING.md` for details on

markdown-mode.el

@@ -7,7 +7,7 @@
 ;; Maintainer: Jason R. Blevins <[email protected]>
 ;; Created: May 24, 2007
 ;; Version: 2.6-alpha
-;; Package-Requires: ((emacs "26.1"))
+;; Package-Requires: ((emacs "27.1"))
 ;; Keywords: Markdown, GitHub Flavored Markdown, itex
 ;; URL: https://jblevins.org/projects/markdown-mode/
 

tests/markdown-test.el

@@ -5671,10 +5671,7 @@ indented the same amount."
       (let ((fill-column 10))
         (end-of-line)
         (funcall auto-fill-function)
-        ;; This test was known to fail in Emacs 25 and earlier.
-        (if (version< emacs-version "26.0")
-            (should-not (string-equal (buffer-string) str))
-          (should (string-equal (buffer-string) str)))))))
+        (should (string-equal (buffer-string) str))))))
 
 (ert-deftest test-markdown-filling/break-within-list-item ()
   "This doesn't suppress auto-fill within a multi-word list item."