Change: Update dependencies and require Go 1.23 or newer

All dependencies have been updated. Rest-server now requires Go 1.23 or newer
to build.

This also disables support for TLS versions older than TLS 1.2. On Windows,
rest-server now requires at least Windows 10 or Windows Server 2016. On macOS,
rest-server now requires at least macOS 11 Big Sur.

https://github.com/restic/rest-server/pull/322
https://github.com/restic/rest-server/pull/338