feat(preset): Add SlackNet monorepo (#31589)

Author: sommmen

lib/data/monorepo.json

@@ -483,6 +483,7 @@
     "shopify-app-bridge": "https://github.com/Shopify/app-bridge",
     "sitecore-jss": "https://github.com/Sitecore/jss",
     "skiasharp": "https://github.com/mono/SkiaSharp",
+    "slack-net": "https://github.com/soxtoby/SlackNet",
     "slf4j": "https://github.com/qos-ch/slf4j",
     "spectre-console": "https://github.com/spectreconsole/spectre.console",
     "springfox": "https://github.com/springfox/springfox",