Fallback to default buffer size

Also fixes a bug when using Spectre.Console in GitHub Actions.

.github/workflows/ci.yaml

@@ -31,6 +31,16 @@ jobs:
         with:
           dotnet-version: 3.1.301
 
+      - name: Integration Tests
+        shell: bash
+        run: |
+          dotnet tool restore
+          dotnet example diagnostic
+          dotnet example table
+          dotnet example grid
+          dotnet example panel
+          dotnet example colors
+
       - name: Build
         shell: bash
         run: |