Merge #603

603: Make RankingScoreThreshold optional r=curquiza a=danFbach

# Pull Request

## Related issue
Fixes #601 

## What does this PR do?
- make RankingScoreThreshold nullable (thereby optional and ignored by json convertor if left null)

## PR checklist
Please check if your PR fulfills the following requirements:
- [x] Does this PR fix an existing issue, or have you listed the changes applied in the PR description (and why they are needed)?
- [x] Have you read the contributing guidelines?
- [x] Have you made sure that the title is accurate and descriptive of the changes?

Passes all current integration tests.


Co-authored-by: Dan Fehrenbach <[email protected]>

Author: meili-bors[bot]

src/Meilisearch/SearchQuery.cs

@@ -147,6 +147,6 @@ public class SearchQuery
         /// Gets or sets rankingScoreThreshold, a number between 0.0 and 1.0. 
         /// </summary>
         [JsonPropertyName("rankingScoreThreshold")]
-        public decimal RankingScoreThreshold { get; set; }
+        public decimal? RankingScoreThreshold { get; set; }
     }
 }