Update tool to parse 3.1 docs

Author: MaggieKimani1

src/Microsoft.OpenApi.Workbench/MainModel.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft Corporation. All rights reserved.
+// Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license.
 
 using System;
@@ -11,6 +11,7 @@
 using Microsoft.OpenApi.Extensions;
 using Microsoft.OpenApi.Models;
 using Microsoft.OpenApi.Reader;
+using Microsoft.OpenApi.Readers;
 using Microsoft.OpenApi.Services;
 using Microsoft.OpenApi.Validations;
 
@@ -158,6 +159,7 @@ public OpenApiSpecVersion Version
                 _version = value;
                 OnPropertyChanged(nameof(IsV2_0));
                 OnPropertyChanged(nameof(IsV3_0));
+                OnPropertyChanged(nameof(IsV3_1));
             }
         }
 
@@ -185,6 +187,12 @@ public bool IsV3_0
             set => Version = OpenApiSpecVersion.OpenApi3_0;
         }
 
+        public bool IsV3_1
+        {
+            get => Version == OpenApiSpecVersion.OpenApi3_1;
+            set => Version = OpenApiSpecVersion.OpenApi3_1;
+        }
+
         /// <summary>
         /// Handling method when the property with given name has changed.
         /// </summary>

src/Microsoft.OpenApi.Workbench/MainWindow.xaml

@@ -40,6 +40,7 @@
                     </StackPanel>
                     <StackPanel Orientation="Horizontal" VerticalAlignment="Center">
                         <Label>Version:</Label>
+                        <RadioButton GroupName="Format" Content="V3.1.0" Padding="5" Height="24" VerticalAlignment="Top" IsChecked="{Binding IsV3_1}" />
                         <RadioButton GroupName="Format" Content="V3.0.1" Padding="5" Height="24" VerticalAlignment="Top" IsChecked="{Binding IsV3_0}" />
                         <RadioButton GroupName="Format" Content="V2.0" Padding="5" Height="24" VerticalAlignment="Top" IsChecked="{Binding IsV2_0}" />
                     </StackPanel>