Configure Dependabot for NuGet package updates (#3271)

Author: torosent

.github/dependabot.yml

@@ -1,5 +1,15 @@
 version: 2
 updates:
+  - package-ecosystem: "nuget"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+      day: "tuesday"
+    ignore:
+      - dependency-name: "*"
+        update-types: 
+          - "version-update:semver-major"
+
   - package-ecosystem: "dotnet-sdk"
     directory: "/"
     schedule:
@@ -9,4 +19,3 @@ updates:
       - dependency-name: "*"
         update-types: 
           - "version-update:semver-major"
-          - "version-update:semver-minor"