Treat DISM as unavailable when DismApi.dll can't be loaded - #480

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: microsoft/setup-msbuild@v2, nuget/setup-nuget@v2. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/