Add GeohexGrid aggregation (#1591)

(cherry picked from commit acd63a8)

Author: Telomeraz

elasticsearch_dsl/aggs.py

@@ -209,6 +209,10 @@ class GeohashGrid(Bucket):
     name = "geohash_grid"
 
 
+class GeohexGrid(Bucket):
+    name = "geohex_grid"
+
+
 class GeotileGrid(Bucket):
     name = "geotile_grid"
 

tests/test_aggs.py

@@ -262,6 +262,12 @@ def test_geohash_grid_aggregation():
     assert {"geohash_grid": {"field": "centroid", "precision": 3}} == a.to_dict()
 
 
+def test_geohex_grid_aggregation():
+    a = aggs.GeohexGrid(**{"field": "centroid", "precision": 3})
+
+    assert {"geohex_grid": {"field": "centroid", "precision": 3}} == a.to_dict()
+
+
 def test_geotile_grid_aggregation():
     a = aggs.GeotileGrid(**{"field": "centroid", "precision": 3})