Test other syntax for build_args

.woodpecker.yml

@@ -10,7 +10,7 @@ steps:
       platforms: linux/arm64/v8
       tag: *flutter_version
       build_args:
-        FLUTTER_VERSION: *flutter_version
+        - FLUTTER_VERSION=3.13.6
       auto_tag: true
       username:
         from_secret: repository_username

Dockerfile

@@ -3,6 +3,8 @@ FROM debian:bookworm-20230919-slim
 # The version of Flutter to use
 ARG FLUTTER_VERSION
 
+RUN echo $FLUTTER_VERSION
+
 # Set environment variables
 ENV PATH="$PATH:/opt/flutter/bin"