fix(init): remove build-deps

Remove build-depds after build-script is executed by Python.  This reduces the attack surface of the container, as leaving python3 installed in a rootfull container is a risk

docker/root/etc/cont-init.d/50-config

@@ -41,6 +41,10 @@ cp /app/themepark/CNAME /config/www
 echo 'Creating CSS files'
 python3 /config/www/themes.py
 
+# remove build deps
+# to reduce attack surface
+apk del build-dependencies
+
 # permissions
 chown -R abc:abc \
-    /config
+    /config