feat: add build workflows

- enable fetch-depth for code_checkout
- fetch master branch before checking for changed files
- ensure the clean target is called with the default

ci/build.sh

@@ -1,6 +1,7 @@
 #!/bin/bash
 
 # Check for changes in images/ folder and the builds/ folder
+git fetch origin master:master
 if [ "$(git branch --show-current)" = "master" ]; then
   builds_changes=$(git diff --name-only HEAD^...master | grep -E '^builds/')
   images_changes=$(git diff --name-only HEAD^...master | grep -E '^images/')