Search select multi option

[lbrito1]

Motivation / Background

This PR changes the behaviour of SearchSelectFilterInput such that it is now possible to use a multi-value (input_html: { multiple: true }) input.

Detail

I needed the search select filter with multiple values in my app, within the same model (e.g. filtering User.name in the ActiveAdmin User page).

Currently, to the best of my knowledge, this was not possible because SearchSelectFilterInput#input_method was hardcoded to use eq, which breaks ransack at some point with an error like "cannot use eq for [123, 456]" if you try to use multiple: true.

This PR changes SearchSelectFilterInput#input_method to use an appropriate predicate for lists (in) when needed (e.g. when input_html: { multiple: true }).

I had to update some minor gem versions to get bin/setup working.

Additional information

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Changes that are unrelated should be opened in separate PRs.
• Commit message has a concise description of what changed and why.
• Tests are added or updated if you fix a bug or add a feature.
• [X Documentation has been added or updated if you add a feature or modify an existing one.
• CHANGELOG files are updated for the changed libraries if there is a behavior change or additional feature (under the "Unreleased" heading if this is not a version change).
• My changes don't introduce any linter rule violations.