Update TFM to .NET 9.0 and create shared dotnet setup action

Co-authored-by: BenjaminMichaelis <22186029+BenjaminMichaelis@users.noreply.github.com>

Author: Copilot

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

@@ -0,0 +1,10 @@
+name: 'Setup .NET'
+description: 'Setup .NET SDK using global.json configuration'
+
+runs:
+  using: 'composite'
+  steps:
+    - name: Setup .NET
+      uses: actions/setup-dotnet@v5
+      with:
+        global-json-file: global.json

.github/workflows/build-and-test.yml

@@ -33,9 +33,7 @@ jobs:
     steps:
     - uses: actions/checkout@v5
     - name: Setup .NET
-      uses: actions/setup-dotnet@v5
-      with:
-        dotnet-version: 8.x
+      uses: ./.github/actions/setup-dotnet
     - name: Setup Dependency Caching
       uses: actions/cache@v4
       id: nuget-cache

.github/workflows/deploy.yml

@@ -17,9 +17,7 @@ jobs:
     steps:
     - uses: actions/checkout@v5
     - name: Setup .NET
-      uses: actions/setup-dotnet@v5
-      with:
-        dotnet-version: 8.0
+      uses: ./.github/actions/setup-dotnet
     - name: Setup Dependency Caching
       uses: actions/cache@v4
       id: nuget-cache

ListingManager.Tests/EssentialCSharp.ListingManager.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFramework>net8.0</TargetFramework>
+        <TargetFramework>net9.0</TargetFramework>
         <IsPackable>false</IsPackable>
     </PropertyGroup>
 

ListingManager/EssentialCSharp.ListingManager.csproj

@@ -2,7 +2,7 @@
 
 	<PropertyGroup>
 		<OutputType>Exe</OutputType>
-		<TargetFramework>net8.0</TargetFramework>
+		<TargetFramework>net9.0</TargetFramework>
 		<PackAsTool>true</PackAsTool>
 		<ToolCommandName>ListingManager</ToolCommandName>
 		<RepositoryType>git</RepositoryType>

global.json

@@ -0,0 +1,6 @@
+{
+  "sdk": {
+    "version": "9.0.0",
+    "rollForward": "latestMinor"
+  }
+}