Fix kirby-slides breaking when slides input is updated

[RasmusKjeldgaard]

Which issue does this PR close?

This PR closes #3112

What is the new behavior?

When kirby-slides slides input is updated asynchronosly, but with a new object that causes us to re-render the individual slides without re-rendering the slides template itself, swiper.js no longer has the correct slide element references to apply its styles/calculations to, causing the slides to lose all config like slides per view, gap etc.

Does this PR introduce a breaking change?

• Yes
• No

Checklist:

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When the pull request has been approved it will be merged to develop by Team Kirby.