use gleam 1.16

Author: kwando

.github/workflows/test.yml

@@ -15,7 +15,7 @@ jobs:
       - uses: erlef/setup-beam@v1
         with:
           otp-version: "28"
-          gleam-version: "1.15.0-rc1"
+          gleam-version: "1.16.0"
           rebar3-version: "3"
           # elixir-version: "1"
       - uses: mfinelli/setup-imagemagick@v3