ci: bump RIOT_BRANCH and VERSION_TAG to 2025.01-branch and 2025.04#257

chrysn merged 1 commit intoRIOT-OS:masterRIOT-OS/riotdocker:masterfrom

chrysn-pull-requests:update-brancheschrysn-pull-requests/riotdocker:update-branchesCopy head branch name to clipboard