updated Public.approved.txt file to include two methods now being virtual

Author: peteraritchie

test/Microsoft.OpenApi.Tests/PublicApi/PublicApi.approved.txt

@@ -979,8 +979,8 @@ namespace Microsoft.OpenApi.Services
         protected OpenApiVisitorBase() { }
         public Microsoft.OpenApi.Services.CurrentKeys CurrentKeys { get; }
         public string PathString { get; }
-        public void Enter(string segment) { }
-        public void Exit() { }
+        public virtual void Enter(string segment) { }
+        public virtual void Exit() { }
         public virtual void Visit(Microsoft.OpenApi.Interfaces.IOpenApiExtensible openApiExtensible) { }
         public virtual void Visit(Microsoft.OpenApi.Interfaces.IOpenApiExtension openApiExtension) { }
         public virtual void Visit(Microsoft.OpenApi.Interfaces.IOpenApiReferenceable referenceable) { }