Drop Elixir 1.9; Update 1.13; Add 1.12, 1.14

Author: J3RN

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
       matrix:
         emacs_version: ['27.2', '26.3', '25.3', 'snapshot']
         otp: ['23.3']
-        elixir: ['1.9.4', '1.11.4', '1.13.3']
+        elixir: ['1.11.4', '1.12.3', '1.13.4', '1.14.3']
 
     steps:
       - name: Setup Emacs