constrain version of elasticsearch client
With the recent upgrade to 7.15
I am observing:
elasticsearch.exceptions.UnsupportedProductError: The client noticed that the server is not a supported distribution of Elasticsearch
Until we move to OpenSearch (see https://gitlab.cern.ch/lhcb-core/nightly-builds/lb-nightly-deployment/-/issues/3, https://github.com/elastic/elasticsearch-py/issues/1639), let's prevent updates of the elasticsearch client.
Edited by Maciej Pawel Szymanski