Add Skipped and Stale CheckConclusionState

Author: jcansdale

src/GitHub.App/Services/FromGraphQlExtensions.cs

@@ -29,6 +29,10 @@ public static class FromGraphQlExtensions
                     return CheckConclusionState.Success;
                 case Octokit.GraphQL.Model.CheckConclusionState.Neutral:
                     return CheckConclusionState.Neutral;
+                case Octokit.GraphQL.Model.CheckConclusionState.Skipped:
+                    return CheckConclusionState.Skipped;
+                case Octokit.GraphQL.Model.CheckConclusionState.Stale:
+                    return CheckConclusionState.Stale;
                 default:
                     throw new ArgumentOutOfRangeException(nameof(value), value, null);
             }

src/GitHub.Exports/Models/CheckConclusionState.cs

@@ -8,5 +8,7 @@ public enum CheckConclusionState
         Failure,
         Success,
         Neutral,
+        Skipped,
+        Stale
     }
 }