Client support for Rekor V2: sigstore-python

Description

For the endpoint to post new entries, the client will have a trailing slash. This does not seem to be according to rekor V1 spec, but will still work. The spec is the same in rekorV2, but currently does not work in rekor V2 servers.

• https://github.com/sigstore/rekor/blob/140f622a85d9eeb72677f6ab7de21744954eb4cc/pkg/generated/client/entries/entries_client.go#L97
• https://github.com/sigstore/rekor-tiles/blob/364926072f047df0cd4a9c3285c52e2f7f2d5dc9/api/proto/rekor_service.proto#L32-L37