Remove dependabot tracting for nuget packages (#1944)

Co-authored-by: Dave Thaler <dthaler@microsoft.com>

.github/dependabot.yml

@@ -21,12 +21,6 @@ updates:
       interval: "weekly"
       day: "saturday"
 
-  - package-ecosystem: "nuget"
-    directory: "/"
-    schedule:
-      interval: "weekly"
-      day: "saturday"
-
   - package-ecosystem: "docker"
     directory: "/images"
     schedule: