Handle case where table-filter is not found

[rzane]

When there are no standard personas, the input[data-behavior=table-filter] element won't exist (see here). As a result, the following JS error is thrown:

TypeError: Cannot set properties of null (setting 'oninput')

This PR does an early return if that input is not found.

In addition to this bugfix, the following maintenance has been performed:

• Bumped the version.
• Switch to Cuprite. It's simpler to configure and would have caught this error with js_errors: true.
• Removed Ruby 2.7 from the build matrix.
• Removed Rails 6.0 from the build matrix.
• Added Ruby 3.2 to the build matrix.
• Fixed new Rubocop violations.

[smudge]

Looks like Rubocop is still running with TargetRubyVersion 2.7 and complaining.