chore: update banners

banners https://github.com/ory/meta/tree/master/static/banners need an update
also Polis does not have a banner yet

they are mainly used in the README as .svg - see here for example. https://github.com/ory/kratos/blob/354a074dfeb59b7aa8843d893b1ed8be26ac89c8/README.md?plain=1#L1

we can also use them to embed in other places.
