Fix: mktemp not working correctly on Alpine Linux #284

[jxinging]

Resolves: #284

[Samusia]

@jxinging 0.11.14 does not work since the last few PRs

docker run -it --rm openresty/openresty:1.19.3.2-3-alpine-fat /bin/bash
apk add git && git clone https://github.com/tfutils/tfenv.git ~/.tfenv

I made changes manually from this PR

tfenv install 0.11.14
Installing Terraform v0.11.14
Downloading release tarball from https://releases.hashicorp.com/terraform/0.11.14/terraform_0.11.14_linux_arm64.zip
curl: (22) The requested URL returned error: 403

Tarball download failed