Fix VM tests.

Makefile

@@ -37,15 +37,15 @@ test: test-vm test-tx
 	$(CARGO) test --release --all-features --all
 
 test-tx:
-	$(CARGO) run --release --features=node --example tx
+	$(CARGO) run --release --features=node,zkas --example tx
 
 VM_SRC = proof/mint.zk proof/burn.zk
 VM_BIN = $(VM_SRC:=.bin)
 
-$(VM_BIN): $(VM_SRC)
+$(VM_BIN): zkas $(VM_SRC)
 	./zkas $(basename $@) -o $@
 
-test-vm:
+test-vm: $(VM_BIN)
 	$(CARGO) run --release --features=cli,crypto,zkas --example mint
 	$(CARGO) run --release --features=cli,crypto,zkas --example burn