Repository: elastic/elasticsearch-dsl-py

Issue:
Add support for "matrix_stats" metrics aggregation
`elasticsearch_dsl/aggs.py` is missing "matrix_stats" metrics aggregation. [Matrix stats aggregation](https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-matrix-stats-aggregation.html)

Discussion:

Patch:
diff --git a/elasticsearch_dsl/aggs.py b/elasticsearch_dsl/aggs.py
index 8f91333..61a27f3 100644
--- a/elasticsearch_dsl/aggs.py
+++ b/elasticsearch_dsl/aggs.py
@@ -333,6 +333,10 @@ class Max(Agg):
     name = "max"
 
 
+class MatrixStats(Agg):
+    name = "matrix_stats"
+
+
 class MedianAbsoluteDeviation(Agg):
     name = "median_absolute_deviation"
 


Test patch:
diff --git a/tests/test_aggs.py b/tests/test_aggs.py
index 0874a66..3278928 100644
--- a/tests/test_aggs.py
+++ b/tests/test_aggs.py
@@ -341,6 +341,12 @@ def test_inference_aggregation():
     } == a.to_dict()
 
 
+def test_matrix_stats_aggregation():
+    a = aggs.MatrixStats(fields=["poverty", "income"])
+
+    assert {"matrix_stats": {"fields": ["poverty", "income"]}} == a.to_dict()
+
+
 def test_moving_percentiles_aggregation():
     a = aggs.DateHistogram()
     a.bucket("the_percentile", "percentiles", field="price", percents=[1.0, 99.0])