Fix support for Windows Batch
Test builds:
- https://gitlab-ci-multi-runner-downloads.s3.amazonaws.com/fix-cmd-shell/binaries/gitlab-ci-multi-runner-linux-386
- https://gitlab-ci-multi-runner-downloads.s3.amazonaws.com/fix-cmd-shell/binaries/gitlab-ci-multi-runner-linux-amd64
- https://gitlab-ci-multi-runner-downloads.s3.amazonaws.com/fix-cmd-shell/binaries/gitlab-ci-multi-runner-linux-arm
- https://gitlab-ci-multi-runner-downloads.s3.amazonaws.com/fix-cmd-shell/binaries/gitlab-ci-multi-runner-darwin-386
- https://gitlab-ci-multi-runner-downloads.s3.amazonaws.com/fix-cmd-shell/binaries/gitlab-ci-multi-runner-darwin-amd64
- https://gitlab-ci-multi-runner-downloads.s3.amazonaws.com/fix-cmd-shell/binaries/gitlab-ci-multi-runner-windows-386.exe
- https://gitlab-ci-multi-runner-downloads.s3.amazonaws.com/fix-cmd-shell/binaries/gitlab-ci-multi-runner-windows-amd64.exe
- https://gitlab-ci-multi-runner-downloads.s3.amazonaws.com/fix-cmd-shell/binaries/gitlab-ci-multi-runner-freebsd-386
- https://gitlab-ci-multi-runner-downloads.s3.amazonaws.com/fix-cmd-shell/binaries/gitlab-ci-multi-runner-freebsd-amd64
- https://gitlab-ci-multi-runner-downloads.s3.amazonaws.com/fix-cmd-shell/binaries/gitlab-ci-multi-runner-freebsd-arm
Fixes https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/issues/1052