fix: golang 1.21, race condition detector

[AVVS]

docker buildx build --build-arg VERSION=dev-race --build-arg TARGET_DB=mongodb --build-arg PLATFORM=arm64 -f docker/tinode/Dockerfile ./ --platform=linux/arm64 --tag gcr.io/<project>/tinode-mongodb:2024-01-17-dev.race-detector.0 --push

builds the image