build: Github workflow - added .net 9 to CI, updated action versions

Author: anthonyreilly

.github/workflows/ci.yml

@@ -18,27 +18,27 @@ jobs:
       config: "Release"
 
     steps:
-      - uses: actions/checkout@v3
-
-      - name: Setup .NET Core 2.1
-        uses: actions/setup-dotnet@v3
-        with:
-          dotnet-version: 2.1.x
-
-      - name: Setup .NET Core 3.1
-        uses: actions/setup-dotnet@v3
-        with:
-          dotnet-version: 3.1.x
+      - uses: actions/checkout@v4
 
       - name: Setup .NET Core 6.0
-        uses: actions/setup-dotnet@v3
+        uses: actions/setup-dotnet@v4
         with:
           dotnet-version: 6.0.x
 
       - name: Setup .NET Core 7.0
-        uses: actions/setup-dotnet@v3
+        uses: actions/setup-dotnet@v4
         with:
           dotnet-version: 7.0.x
+      
+      - name: Setup .NET Core 8.0
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: 8.0.x
+
+      - name: Setup .NET Core 9.0
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: 9.0.x
 
       - name: Restore dependencies
         run: dotnet restore