The is-automated field is being deprecated by Docker Hub's search API,
and will always be set to "false" in future.
This patch deprecates the field and related filter for the Engine's API.
In future, the `is-automated` filter will no longer yield any results
when searching for `is-automated=true`, and will be ignored when
searching for `is-automated=false`.
Given that this field is deprecated by an external API, the deprecation
will not be versioned, and will apply to any API version.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
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