The SearchResult class under PlainElastic.Net.Serialization is out of date

[lichen95]

Comparison between elasticsearch6.4.0 and elasticsearch7.3.0 :
elasticsearch6.4.0:

elasticsearch7.3.0

It can be seen that the return value of total changes in the 7.3.0 version, and the previous return result SearchResult class is obsolete.

[lichen95]

Changed from the previous int type

"total": {"value": 10000,
"relation": "gte"
},