Update .NET dependencies to C# 13.0 and .NET 9.0

.github/actions/setup-dotnet/action.yml

@@ -12,9 +12,8 @@ runs:
       uses: actions/setup-dotnet@v5
       with:
         dotnet-version: |
-          6.0.x
-          7.0.x
           8.0.x
+          9.0.x
 
     - name: Set up dependency caching for faster builds
       uses: actions/cache@v4

Common.props

@@ -1,5 +1,5 @@
 <Project>
   <PropertyGroup>
-    <TargetFrameworks>net8.0;net7.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>net9.0;net8.0</TargetFrameworks>
   </PropertyGroup>
 </Project>

Directory.Build.props

@@ -1,6 +1,6 @@
 <Project>
   <PropertyGroup>
-    <LangVersion>12.0</LangVersion>
+    <LangVersion>13.0</LangVersion>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
     <AccelerateBuildsInVisualStudio>true</AccelerateBuildsInVisualStudio>

Errata.md

@@ -1,6 +1,6 @@
-# Essential C# 12.0 Errata Document
+# Essential C# 13.0 Errata Document
 
-## Essential C# 12.0
+## Essential C# 13.0
 
 by Mark Michaelis
 ISBN-13: 978-0138219512

README.md

@@ -8,7 +8,7 @@ This project contains the source code for the book **Essential C#** by Mark Mich
 
 ## Requirements
 
-- [.NET](https://www.microsoft.com/net/core) - This project is currently tested against .NET 8.0, 7.0, and 6.0.
+- [.NET](https://www.microsoft.com/net/core) - This project is currently tested against .NET 9.0 and 8.0.
 - [Visual Studio](https://visualstudio.microsoft.com/downloads/) - Already contains .NET Core to get up and running. Not to mention, it's a great IDE that makes it easy to get started.
 - [Git](https://git-scm.com/book/en/v2/Getting-Started-Installing-Git) - While not required, a good tool to get used to, and easy way to download this code repository quickly. [GitKraken](https://gitkraken.cello.so/tl7bYaRLgzT) is a great GUI for using Git if you prefer not using the command line. Visual Studio and VSCode also have ever improving git tooling built in.
 

global.json

@@ -1,6 +1,6 @@
 {
   "sdk": {
-    "version": "8.0.0",
+    "version": "9.0.0",
     "rollForward": "latestFeature",
     "allowPrerelease": true
   }