Add elasticsearch 7.6.2 for Magento (2.4.x) compatibility

In Magento 2.4.0

"Elasticsearch 7.6.x is now the default catalog search engine for Magento Commerce and Open Source. You cannot install or upgrade to Magento 2.4.0 without also installing Elasticsearch 7.6.x [...] Elasticsearch versions 5.x and 6.x have been deprecated and are no longer supported. [...]"

see: https://devdocs.magento.com/guides/v2.4/release-notes/release-notes-2-4-0-open-source.html#platform-upgrades