Specify Dockerfile syntax version

shepmaster · shepmaster · commit 851050e1d89e · 2023-06-19T21:24:03.000-04:00
diff --git a/compiler/base/Dockerfile b/compiler/base/Dockerfile
@@ -1,3 +1,5 @@
+#syntax=docker/dockerfile:1.5
+
 FROM ubuntu:20.04 as toolchain
 
 ARG channel
