Use windows way of using env variable in shell

Author: justcoding121

.github/workflows/dotnetcore.yml

@@ -47,9 +47,9 @@ jobs:
       if: github.ref == 'refs/heads/beta'
       run: |
        dotnet pack src/Advanced.Algorithms/Advanced.Algorithms.csproj --version-suffix "beta"
-       dotnet nuget push **\*.nupkg -s "nuget" -k $NUGET_TOKEN
+       dotnet nuget push **\*.nupkg -s "nuget" -k %NUGET_TOKEN%
     - name: Publish Stable
       if: github.ref == 'refs/heads/stable'
       run: |
        dotnet pack src/Advanced.Algorithms/Advanced.Algorithms.csproj
-       dotnet nuget push **\*.nupkg -s "nuget" -k $NUGET_TOKEN
+       dotnet nuget push **\*.nupkg -s "nuget" -k %NUGET_TOKEN%