revert changes on .ci/test-matrix.yml and ci/run-repository.sh files

Author: miriam-eid

Diff for: .ci/run-repository.sh

@@ -43,4 +43,4 @@ docker run \
   --name elasticsearch-py \
   --rm \
   elastic/elasticsearch-py \
-  /bin/bash -c "python -m pip install nox && python -m nox -s test-${PYTHON_VERSION}"
+  nox -s test-${PYTHON_VERSION}

Diff for: .ci/test-matrix.yml

@@ -1,5 +1,5 @@
 STACK_VERSION:
-  - "8.6.0-SNAPSHOT"
+  - "8.7.0-SNAPSHOT"
 
 TEST_SUITE:
   - platinum