Build failed if build directory name contains some char, eg: "@"

[yowenter]

https://github.com/rancher/dapper/blob/1119701a49a0f83d46b1e89785e87f17f639a942/file/file.go#L365

DEBU[0000] Building XXX@2:release-develop using Dockerfile.dapper
DEBU[0000] Created tempfile Dockerfile.dapper003042636
DEBU[0000] Running /bin/docker [build -t XXX@2:release-develop --build-arg DAPPER_HOST_ARCH=amd64 -f Dockerfile.dapper003042636 .]
invalid argument "XXX@2:release-develop" for "-t, --tag" flag: invalid reference format