feat: Updates to .NET 8. (#1542)

### Breaking Changes
- Updating to .NET 8 - Required O/S's have slightly changed.

.github/workflows/build-test.yml

@@ -23,10 +23,10 @@ jobs:
     - uses: actions/checkout@v4
       with:
         fetch-depth: 0 # avoid shallow clone so nbgv can do its work.
-    - name: Setup .NET 7
+    - name: Setup .NET 8
       uses: actions/setup-dotnet@v3
       with:
-        dotnet-version: 7.0.x
+        dotnet-version: 8.0.x
     - name: Build
       run: ./publish.cmd Release
     - name: Migration Changes
@@ -45,12 +45,18 @@ jobs:
           - container: ubuntu:jammy
             name: Ubuntu 22
             packageManager: apt
+          - container: ubuntu:focal
+            name: Ubuntu 20
+            packageManager: apt
           - container: debian:bookworm
             name: Debian 12
             packageManager: apt
           - container: debian:bullseye
             name: Debian 11
             packageManager: apt
+          - container: fedora:39
+            name: Fedora 39
+            packageManager: dnf
           - container: fedora:38
             name: Fedora 38
             packageManager: dnf
@@ -77,10 +83,10 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0 # avoid shallow clone so nbgv can do its work.
-      - name: Setup .NET 7
+      - name: Setup .NET 8
         uses: actions/setup-dotnet@v3
         with:
-          dotnet-version: 7.0.x
+          dotnet-version: 8.0.x
       - name: Build
         run: ./publish.sh Release
       - name: Test