feat(ci): the ISO's version follows Steamify: master releases v<steamify>-<date>, feat/steamify a test build v<steamify>-dev.<date>; CachyOS's own ISO workflow only runs in CachyOS's repo

.github/workflows/build.yml

@@ -11,6 +11,9 @@ concurrency:
 
 jobs:
   build:
+    # CachyOS's plain ISO and its quicktest matrix: only in CachyOS's own repo, not in this fork
+    # (the Steamify ISO is steamify-iso.yml).
+    if: github.repository == 'CachyOS/CachyOS-Live-ISO'
     runs-on: ubuntu-latest
     container:
       image: archlinux:base-devel