Add go mod file

go.mod

@@ -0,0 +1,5 @@
+module github.com/aleroyer/sakuin
+
+go 1.18
+
+require github.com/dustin/go-humanize v1.0.0

go.sum

@@ -0,0 +1,2 @@
+github.com/dustin/go-humanize v1.0.0 h1:VSnTsYCnlFHaM2/igO1h6X3HA71jcobQuxemgkq4zYo=
+github.com/dustin/go-humanize v1.0.0/go.mod h1:HtrtbFcZ19U5GC7JDqmcUSB87Iq5E25KnS6fMYU6eOk=