Bump avh4/elm-program-test from 3.6.3 to 3.8.0 in /example

Bumps [avh4/elm-program-test](https://github.com/avh4/elm-program-test) from 3.6.3 to 3.8.0.
- [Release notes](https://github.com/avh4/elm-program-test/releases)
- [Changelog](https://github.com/avh4/elm-program-test/blob/main/CHANGELOG.md)
- [Commits](avh4/elm-program-test@3.6.3...3.8.0)

---
updated-dependencies:
- dependency-name: avh4/elm-program-test
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

example/elm.json

@@ -48,7 +48,7 @@
     },
     "test-dependencies": {
         "direct": {
-            "avh4/elm-program-test": "3.6.3",
+            "avh4/elm-program-test": "3.8.0",
             "elm-explorations/test": "1.2.2"
         },
         "indirect": {