Keep using older version python 3.8

Author: xrmx

opentelemetry-api/test-requirements.txt

@@ -1,6 +1,7 @@
 asgiref==3.7.2
 Deprecated==1.2.14
-importlib-metadata==8.6.1
+importlib-metadata==8.5.0 ; python_version < "3.9"
+importlib-metadata==8.6.1 ; python_version >= "3.9"
 iniconfig==2.0.0
 packaging==24.0
 pluggy==1.5.0