Update package version in GitHub workflow to 5.1.0

In the GitHub Actions workflow file, change the package version from 5.0.0 to 5.1.0 to reflect the new release. This update ensures that the versioning is consistent with the project's release plan.

.github/workflows/main.yml

@@ -25,6 +25,6 @@ jobs:
       - name: Pack
         # CHANGE PACKAGE VERSION - The retarded way
         # Change the /p:VERSION=X.X.X part to change the actual package version.
-        run: dotnet pack --configuration Release /p:VERSION=5.0.0.${{ github.run_number }} --version-suffix ${{ github.sha }}
+        run: dotnet pack --configuration Release /p:VERSION=5.1.0.${{ github.run_number }} --version-suffix ${{ github.sha }}
       - name: Upload to NuGet
         run: dotnet nuget push ./source/X39.Solutions.PdfTemplate/bin/Release/X39.Solutions.PdfTemplate.*.nupkg -s https://api.nuget.org/v3/index.json -k ${{ secrets.NUGET_API_KEY }}