add 1.18.4 explicitly

Author: cschiewek

.github/workflows/elixir.yml

@@ -18,13 +18,16 @@ jobs:
           - "1.16"
           - "1.17"
           - "1.18"
+          - "1.18.4"
         otp:
           - "25"
           - "26"
           - "27"
           - "28"
         # see https://hexdocs.pm/elixir/compatibility-and-deprecations.html#between-elixir-and-erlang-otp
         exclude:
+          - elixir: 1.18
+            otp: 28
           - elixir: 1.17
             otp: 28
           - elixir: 1.16