add quote for path

Author: PerthCharern

src/Microsoft.OpenApi/Validations/Rules/OpenApiParameterRules.cs

@@ -52,7 +52,7 @@ public static class OpenApiParameterRules
                     {
                         context.CreateError(
                             nameof(RequiredMustBeTrueWhenInIsPath),
-                            "\"required\" must be true when parameter location is path");
+                            "\"required\" must be true when parameter location is \"path\"");
                     }
 
                     context.Exit();

test/Microsoft.OpenApi.Tests/Validations/OpenApiParameterValidationTests.cs

@@ -50,7 +50,7 @@ public void ValidateRequiredIsTrueWhenInIsPathInParameter()
             errors.Should().NotBeEmpty();
             errors.Select(e => e.Message).Should().BeEquivalentTo(new[]
             {
-                "\"required\" must be true when parameter location is path"
+                "\"required\" must be true when parameter location is \"path\""
             });
         }
     }