add a formosa dockerfile

Author: fdupress

scripts/docker/Dockerfile.formosa

@@ -0,0 +1,7 @@
+# syntax = devthefuture/dockerfile-x
+
+FROM ./Dockerfile.build as build-formosa
+
+RUN \
+	opam install --deps-only --confirm-level=unsafe-yes jasmin && \
+	opam clean