Remove Grok binary blob from docker image.

[kaladay]

cantaloupe/docker/Linux-JDK16/Dockerfile

Line 37 in 21057cf

RUN wget -q https://github.com/GrokImageCompression/grok/releases/download/v7.6.5/libgrokj2k1_7.6.5-1_amd64.deb \

Grok has some concerning behavior as described here:

• GrokImageCompression urls fail cantaloupe-project/cantaloupe#669 (comment)

Three months ago, the Grok project (https://github.com/GrokImageCompression/grok/) wiped its repository history and removed all old releases. They then released a new library version, and the repository was reset to a completely clean state. We asked about this change on the discussion board, and the question was closed. We asked about it, then, in a ticket/issue, and were told the project would not maintain its previous history or continue to host the old releases...

[wwelling]

cantaloupe-project#677