Add Elixir 1.18.4 and OTP 28.0.1 to CI

Author: kipcole9

.github/workflows/ci.yml

@@ -49,6 +49,8 @@ jobs:
             elixir: "1.17.2-otp-27"
           - otp: "27.2"
             elixir: "1.18.1-otp-27"
+          - otp: "28.0.1"
+            elixir: "1.18.4-otp-27"
             lint: true
     steps:
     # Step: Setup Elixir + Erlang image as the base.