chore(deps): update nix requirement from >=0.28.0, < 0.31 to >=0.28.0, < 0.32 - #167

. $HOME/.cargo/env
#!/bin/sh
# rustup shell setup
# affix colons on either side of $PATH to simplify matching
case ":${PATH}:" in
    *:"$HOME/.cargo/bin":*)
        ;;
    *)
        # Prepending path in case a system-installed rustc needs to be overridden
        export PATH="$HOME/.cargo/bin:$PATH"
        ;;
esac
cargo +$VERSION test --all-features --target $TARGET
    Updating crates.io index
error: failed to get `bitflags` as a dependency of package `jail v0.3.1 (/tmp/cirrus-ci-build)`

Caused by:
  download of config.json failed

Caused by:
  failed to download from `https://index.crates.io/config.json`

Caused by:
  [60] SSL peer certificate or SSH remote key was not OK (SSL certificate OpenSSL verify result: unable to get local issuer certificate (20))

Exit status: 101