Fix for the adapter issues 1065 and 1066

Author: OsirisTerje

GitVersion.yml

@@ -1,4 +1,4 @@
-next-version: 3.14.0
+next-version: 3.15.3
 mode: ContinuousDelivery
 legacy-semver-padding: 5
 build-metadata-padding: 5

src/NUnitEngine/nunit.engine.core/RuntimeFramework.cs

@@ -203,8 +203,11 @@ private Version GetClrVersionForFramework(Version frameworkVersion)
                             return new Version(6, 0, 0);
                         case 7:
                             return new Version(7, 0, 0);
+                        case 8:
+                            return new Version(8, 0, 0);
+                        default:
+                            return new Version(frameworkVersion.Major, 0, 0);
                     }
-                    break;
             }
 
             throw new ArgumentException("Unknown framework version " + frameworkVersion.ToString(), "version");