downgrade for python 3.9

Author: rithikanarayan

pyproject.toml

@@ -22,7 +22,8 @@ keywords = [
 dependencies = [
     "datadog>=0.51.0,<1.0.0",
     "wrapt>=1.11.2,<2",
-    "ddtrace>=4.0.0,<5; python_version>='3.9.0'",
+    "ddtrace>=3.19.1,<4; python_version>='3.9.0' and python_version < '3.10'",
+    "ddtrace>=4.0.0,<5; python_version>='3.10.0'",
     "ujson>=5.9.0",
 ]
 packages = [