allow test failures for Ember 4.8 (#484)

Author: dwickern

.github/workflows/ci.yml

@@ -178,9 +178,11 @@ jobs:
       fail-fast: true
       matrix:
         ember-try-scenario:
-          [ember-lts-3.28, ember-lts-4.4, ember-4.6, ember-4.8, ember-classic]
+          [ember-lts-3.28, ember-lts-4.4, ember-4.6, ember-classic]
         allow-failure: [false]
         include:
+          - ember-try-scenario: ember-4.8
+            allow-failure: true
           - ember-try-scenario: ember-release
             allow-failure: true
           - ember-try-scenario: ember-beta