build(docker): avoid running command twice

Author: thomasleplus

img/Dockerfile

@@ -22,8 +22,7 @@ RUN apk -U upgrade \
     optipng=0.7.8-r0 \
     py3-pip=25.1.1-r0 \
     python3=3.12.11-r0 \
-    && if apk -u list | grep -q -e . ; then \
-      apk -u list ; \
+    && if apk -u list | tee -a /dev/stderr | grep -q -e . ; then \
       exit 1 ; \
     fi \
     && apk cache clean \