Support OTP/28 in CI (#37)

List of changes:
- specific versions as string and use latest version in CI matrix
- bump GitHub actions

Author: kianmeng

.github/workflows/ci.yml

@@ -16,15 +16,15 @@ jobs:
       matrix:
         include:
           - pair:
-              elixir: 1.13.4
-              otp: 24.3.4.17
+              elixir: "1.13"
+              otp: "24"
           - pair:
-              elixir: 1.16.0
-              otp: 26.2.1
+              elixir: "1.18"
+              otp: "28"
             lint: lint
             distribution: distribution
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - uses: erlef/setup-beam@v1
         with: