[stable25] Сorrect hover styles for buttons in TopBar during a call

[Antreesy]

Manual backport of #8661 to stable25

Somehow, :deep(.selector) isn't working in previous version, so it was changed to ::v-deep .selector
Please also check it visually on running stable25 version

🚧 TODO

• Code-review
• Visual check

🏁 Checklist

• 📘 API documentation in docs/ has been updated or is not required
• 📗 User documentation in https://github.com/nextcloud/documentation/tree/master/user_manual/talk has been updated or is not required
• 🔖 Capability is added or not needed

[ShGKme]

Somehow, :deep(.selector) isn't working in previous version, so it was changed to ::v-deep .selector

stable25 already uses Vue 2.7. But this feature also requires a vue-loader minor update (16.9 -> 16.10).

The required minor update was already applied in @nextcloud/webpack-vue-config: https://github.com/nextcloud/webpack-vue-config/releases/tag/v5.4.0

We may apply the latest minor update 5.3.0 -> 5.4.0 of @nextcloud/webpack-vue-config on stable25. Then :deep must work fine.

[nickvergessen]

I prefer ::v-deep() over bumping dependencies on stable branches

[ShGKme]

Please also check it visually on running stable25 version