Use 1.19 as target (#25)

fasmat · web-flow · commit 1d2e1586ca5b · 2022-10-19T16:10:51.000+02:00
diff --git a/go.mod b/go.mod
@@ -1,6 +1,6 @@
 module github.com/spacemeshos/merkle-tree
 
-go 1.18
+go 1.19
 
 require (
 	github.com/minio/sha256-simd v1.0.0
