pin versions for devcontainer

[mpw96]

Fix https://github.com/evcc-io/evcc/issues/25950

Fixes this error at container start:

0.310 (!) The 'moby' option is not supported on Debian 'trixie' because 'moby-cli' and related system packages have been removed from that distribution.
0.310 (!) To continue, either set the feature option '"moby": false' or use a different base image (for example: 'debian:bookworm' or 'ubuntu-24.04').

This pins the devcontainer's

• go version to the one currently used i in evcc (1.25),
• os version to one that supports moby (bookworm).

[andig]

go version to the one currently used i in evcc (1.25),

That lead's to double maintenance. It would make more sense of fix the compatibility issues instead of pinning to an outdated version.