Potential fix for pull request finding 'Call to System.IO.Path.Combine'

Co-authored-by: Copilot Autofix powered by AI <223894421+github-code-quality[bot]@users.noreply.github.com>

Author: lcawl

tests/Elastic.Documentation.Services.Tests/ChangelogServiceTests.cs

@@ -562,7 +562,7 @@ public async Task CreateChangelog_WithIssues_CreatesValidYaml()
 				"https://github.com/elastic/elasticsearch/issues/123",
 				"https://github.com/elastic/elasticsearch/issues/456"
 			],
-			Output = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString())
+			Output = new FileSystem().Path.Combine(new FileSystem().Path.GetTempPath(), Guid.NewGuid().ToString())
 		};
 
 		// Act