set memory_limit to unlimited

Dockerfile

@@ -93,7 +93,7 @@ ENV client_max_body_size=5M \
     max_execution_time=0 \
     max_input_time=-1 \
     max_input_vars=1000 \
-    memory_limit=2G \
+    memory_limit=-1 \
     post_max_size=8M \
     upload_max_filesize=5M \
     variables_order="EGPCS" \