(Fix) Remove redundant 'gsed' dependency check

[vindard]

Description

gsed isn't present on Linux and causes check_dependencies to fail. This PR removes the check which should be fine for Linux machines since sed is pretty standard and should still be ok for MacOS because the gsed dependency is already checked a few lines above this change.

(If missing sed becomes an issue later on for Linux users, we can also create a sed check-and-install like you guys did for gsed and MacOS)

Helps to address Issue #4, I was able to successfully complete $ umbrel-dev init after this change on an Ubuntu 18.04 system

[vindard]

Not sure if this helps but I also got stuck with a bad (old) version of vagrant from apt repository that halted my $ umbrel-dev init run with the **error*** below. I had to update my version to the latest manually, but this script should handle this install/update for Linux machines:

#!/bin/bash

if [[ "$(uname)" == "Linux" ]]; then
  if ! command -v jq >/dev/null 2>&1; then
    sudo apt update && sudo apt install jq -y
  fi
  vagrant_deb=$(echo "https://releases.hashicorp.com/vagrant/$(curl -s https://checkpoint-api.hashicorp.com/v1/check/vagrant | jq -r -M '.current_version')/vagrant_$(curl -s https://checkpoint-api.hashicorp.com/v1/check/vagrant | jq -r -M '.current_version')_$(uname -m).deb")
  wget -c $vagrant_deb
  sudo dpkg -i $vagrant_deb
  rm $(basename $vagrant_deb)
fi

---

**error*** - conflicting dependencies fog-core (~> 1.43.0) and fog-core (= 1.45.0)

[mayankchhabra]

Hey, thanks for your PR, @vindard! LGTM.

Luke's away for a couple of days and since I'm not very familiar with the working of umbrel-dev, I'll wait for him to be back so he can chime in.

[vindard]

Sure no probs, I bet it'd be useful as documentation here if anyone runs across the same thing and comes poking around the issue tracker either way

[lukechilds]

Thanks for this @vindard!

Apologies for the slow response, looks great.