Hardcode xz threads to 12

.gitlab-ci.yml

@@ -2,6 +2,10 @@ stages:
   - build
   - publish
 
+cache:
+  - paths:
+    - ZynthianOS/src/workspace/*.img.xz
+
 build-zynthbox-image-armhf:
   tags:
     - arm64
@@ -37,10 +41,10 @@ build-zynthbox-image-armhf:
     - bash -x ./build_dist
     - mv ./workspace/*.img ./workspace/$image_name
     - echo "Image Size -> $(du -h ./workspace/$image_name)"
-    
+
     # Compress image
     - echo "# Compress image"
-    - xz -zv --threads=$(nproc) --memory=90% ./workspace/$image_name
+    - xz -zv --threads=12 --memory=100% ./workspace/$image_name
     - echo "Compressed Image Size -> $(du -h ./workspace/$image_name.xz)"
 
     # Ensuring key security