tests: Rename test method for clarity

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: baywet

test/Microsoft.OpenApi.Readers.Tests/V32Tests/OpenApiDocumentTests.cs

@@ -625,7 +625,7 @@ public async Task DocumentWithSchemaResultsInWarning()
         }
 
         [Fact]
-        public void ParseEmptyMemoryStreamReturnsDiagnostic()
+public void LoadEmptyMemoryStreamReturnsDiagnostic()
         {
             var result = OpenApiDocument.Load(new MemoryStream());