ci: define PACKER_CONFIG_DIR env var for caching

Signed-off-by: Vojtěch Mareš <vojtech@mares.cz>

.gitlab-ci.yml

@@ -5,6 +5,7 @@ image:
 variables:
   PACKER_LOG: 1          # enable detailed logging
   PACKER_VAR_FILE: "vars.pkrvars.hcl"
+  PACKER_CONFIG_DIR: $CI_PROJECT_DIR
 
 stages:
   - validate
@@ -27,7 +28,7 @@ validate:
   cache:
     key: "packer-plugins"  # Define a key for Packer plugins
     paths:
-      - "~/.config/packer"  # Or your specific plugin path
+      - "$PACKER_CONFIG_DIR/.packer.d"
 
 build-image:
   extends: .parallel