add lower bound on fmt

Author: jchavarri

packages/opam-check-npm-deps/opam-check-npm-deps.1.0.0/opam

@@ -15,6 +15,7 @@ depends: [
   "opam-client" {>= "2.1.2" & < "2.2.0"}
   "mccs" {>= "1.1+14"}
   "angstrom" {>= "0.15.0"}
+  "fmt" {>= "0.9.0"}
   "bos"
   "lwt_ppx"
   "ppx_deriving_yojson"