fix: only run packer validation if any packer-related files were changed.

These files rarely change - and usually by me - so it shouldn't impact PRs from other collaborators very often.

.github/workflows/lint.yml

@@ -46,9 +46,15 @@ jobs:
           version: latest
       - name: Run packer init
         run: "make image/init/digitalocean"
+      - name: Get changed files in the docs folder
+        id: changed-files-specific
+        uses: tj-actions/changed-files@v35.9.2
+        with:
+          files: contrib/images/digitalocean/**
       - name: Run `packer validate`
         env:
           DIGITALOCEAN_TOKEN: ${{ secrets.DIGITALOCEAN_TOKEN }}
+        if: steps.changed-files-specific.outputs.any_changed == 'true'
         run: "make image/validate/digitalocean"
 
   shellcheck: