[.NET] Update versions to 8 & 9

Version 6 and 7 are no longer supported, so we will update it
accordingly

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

@@ -14,7 +14,7 @@ runs:
         uses: actions/setup-dotnet@v4
         with:
           dotnet-version: |
-            8.0.x
+            9.x.x
 
       - name: Restore Dependencies
         run: dotnet restore
@@ -30,4 +30,4 @@ runs:
         if: ${{ inputs.build == 'true' }}
         run: dotnet build --configuration Release --no-restore
         working-directory: ./
-        shell: bash
+        shell: bash

CHANGELOG.md

@@ -0,0 +1,9 @@
+# Aptos Dotnet SDK Changelog
+
+All notable changes to the Aptos Python SDK will be captured in this file. This changelog is written by hand for now.
+
+## Unreleased
+
+- Remove support for .NET 6 and 7, add support for .NET 9
+
+## Beta v0.0.15-beta

Directory.Build.props

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <!-- There should only be one <DefaultVersion> in the file. If moved, it should be updated in the GitHub Actions workflow. -->
     <DefaultVersion>0.0.15</DefaultVersion>
-    <DefaultTargetFrameworks>net8.0;net7.0;net6.0;netstandard2.1</DefaultTargetFrameworks>
+    <DefaultTargetFrameworks>net9.0;net8.0;netstandard2.1</DefaultTargetFrameworks>
     <DefaultTestingFrameworks>net8.0</DefaultTestingFrameworks>
   </PropertyGroup>
 
@@ -15,4 +15,4 @@
     <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
     <GenerateBindingRedirectsOutputType>true</GenerateBindingRedirectsOutputType>
   </PropertyGroup>
-</Project>
+</Project>