.Net: Use UriKind.Relative (#10123)

### Motivation and Context

Closes #9264
Closes #10105 

### Description

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### Contribution Checklist

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- [ ] The code builds clean without any errors or warnings
- [ ] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
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script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [ ] All unit tests pass, and I have added new tests where possible
- [ ] I didn't break anyone 😄

dotnet/samples/LearnResources/Plugins/GitHub/GitHubPlugin.cs

@@ -99,7 +99,7 @@ private static async Task<JsonDocument> MakeRequestAsync(HttpClient client, stri
         Console.WriteLine($"REQUEST: {path}");
         Console.WriteLine();
 
-        HttpResponseMessage response = await client.GetAsync(new Uri(path));
+        HttpResponseMessage response = await client.GetAsync(new Uri(path, UriKind.Relative));
         response.EnsureSuccessStatusCode();
         string content = await response.Content.ReadAsStringAsync();
         return JsonDocument.Parse(content);