add unit test for config module

test/weather_portal_test.gleam

@@ -3,11 +3,3 @@ import gleeunit
 pub fn main() -> Nil {
   gleeunit.main()
 }
-
-// gleeunit test functions end in `_test`
-pub fn hello_world_test() {
-  let name = "Joe"
-  let greeting = "Hello, " <> name <> "!"
-
-  assert greeting == "Hello, Joe!"
-}