Upgrade Elasticsearch version to 7.16.2

[duffn]

Description of problem

The plugin is using a vulnerable version of Elasticsearch. It should be upgraded to version 7.16.2 as per this Dependabot update: https://github.com/dokku/dokku-elasticsearch/pull/98

How reproducible

Steps to Reproduce

1. Install the plugin

Actual Results

Version 7.14.2 is running: https://github.com/dokku/dokku-elasticsearch/blob/master/Dockerfile

Expected Results

The plugin should run Log4j patched version 7.16.2.

Environment Information

dokku report APP_NAME output

Affected in all apps that use the plugin.

How (deb/make/rpm) and where (AWS, VirtualBox, physical, etc.) was Dokku installed?:

Additional information

• App container inspect output (if applicable) via dokku ps:inspect APP_NAME
• The nginx configuration (if applicable) via dokku nginx:show-config APP_NAME
• Link to the exact repository being deployed (if possible/applicable):
• Output of failing Dokku commands after running dokku trace:on (BEWARE: trace:on will print environment variables for some commands, be sure you're not exposing any sensitive information when posting issues. You may replace these values with XXXXXX):

[josegonzalez]

This is done. Thanks for reporting.