irmin-pack: remove pin-depend on Index

Author: craigfe

Diff for: irmin-pack.opam

@@ -16,14 +16,10 @@ depends: [
   "ocaml"      {>= "4.02.3"}
   "dune"       {>= "1.8.0"}
   "irmin"      {>= "2.0.0"}
-  "index"      {>= "1.2.0"}
+  "index"      {>= "1.2.1"}
   "lwt"
   "irmin-test" {with-test & >= "2.0.0"}
   "alcotest-lwt" {with-test}
 ]
 
-pin-depends: [
-  "index.dev" "git+https://github.com/mirage/index#c3ec368842a113dea23788ffd8c2fa7393a6e4f1"
-]
-
 synopsis: "Irmin backend which stores values in a pack file"