dev/sg: fix asdf setup when plugin already added

Created by: bobheadxi

Fixes issues like:

Trying my hardest to fix "Programming languages & tooling" automatically...
✱ Fixing "go"...
Plugin named golang already added
❗️ Failed to fix "go": exit status 2: Plugin named golang already added
✱ Fixing "yarn"...
Running `brew update --auto-update`...
Warning: gnupg 2.3.6 is already installed and up-to-date.
To reinstall 2.3.6, run:
  brew reinstall gnupg
updating plugin repository...HEAD is now at a1c0673 chore: format README.md
Plugin named yarn already added
❗️ Failed to fix "yarn": exit status 2: Plugin named yarn already added
✱ Fixing "node"...
Plugin named nodejs already added
❗️ Failed to fix "node": exit status 2: Plugin named nodejs already added
✱ Fixing "rust"...
Plugin named rust already added
❗️ Failed to fix "rust": exit status 2: Plugin named rust already added
❌ 3. Programming languages & tooling - Some checks are still not satisfied
❌ Programming languages & tooling: failed to fix category automatically

Test plan

for @burmudar to try 😋