pkg(cagent): update go to 1.25.4

[crazy-max]

relates to https://github.com/docker/packaging/actions/runs/19640848065/job/56243606401#step:7:1260

0.292 + go build -trimpath '-ldflags=-w -X github.com/docker/cagent/pkg/version.Version=v0.0.0-20251124141232-c519da0 -X github.com/docker/cagent/pkg/version.Commit=c519da0065472798b82d09bdea2c350af83a8cca' -o bin/cagent .
0.297 go: go.mod requires go >= 1.25.4 (running go 1.25.3; GOTOOLCHAIN=local)
0.298 error: Bad exit status from /var/tmp/rpm-tmp.msB4TN (%build)
0.298     Bad exit status from /var/tmp/rpm-tmp.msB4TN (%build)