Complete dependency updater configuration (#243)

chore: complete dependency updater configuration

- Add missing registries array to updater.yml updates section
- Add labels field for PR labeling (dependencies, nuget)
- Add commit-message configuration (prefix: chore, include: scope)
- Create nuget.config with public NuGet.org registry

These changes ensure the Aviationexam.DependencyUpdater GitHub Action
works correctly by providing complete configuration as per documentation.

Author: trejjam

.github/updater.yml

@@ -12,6 +12,14 @@ updates:
     target-branch: "main"
     targetFramework: net10.0
     execute-restore: true
+    registries:
+      - nuget
+    labels:
+      - "dependencies"
+      - "nuget"
+    commit-message:
+      prefix: "chore"
+      include: "scope"
     groups:
       microsoft:
         patterns:

nuget.config

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+    <packageSources>
+        <clear />
+        <add key="nuget"
+             value="https://api.nuget.org/v3/index.json"
+             protocolVersion="3" />
+
+    </packageSources>
+    <packageSourceMapping>
+        <packageSource key="nuget">
+            <package pattern="*" />
+        </packageSource>
+    </packageSourceMapping>
+</configuration>