Re-enable the mysqlclient-newest 3.11 tests (#1864)

Co-authored-by: Benjamin Wohlwend <[email protected]>

Author: basepi

.ci/.matrix_exclude.yml

@@ -198,6 +198,3 @@ exclude:
     FRAMEWORK: grpc-1.24
   - VERSION: python-3.11
     FRAMEWORK: grpc-1.24
-  # temporary, see https://github.com/elastic/apm-agent-python/pull/1863
-  - VERSION: python-3.11
-    FRAMEWORK: mysqlclient-newest