Apply suggestions from code review

Co-authored-by: Jan Midtgaard <[email protected]>

Author: c-cube

packages/ocaml-protoc/ocaml-protoc.4.0/opam

@@ -16,7 +16,7 @@ depends: [
   "ocaml" {>= "4.08"}
 ]
 build: [
-  ["dune" "subst"] {pinned}
+  ["dune" "subst"] {dev}
   [
     "dune"
     "build"

packages/pbrt/pbrt.4.0/opam

@@ -15,7 +15,7 @@ depends: [
 dev-repo: "git+https://github.com/mransan/ocaml-protoc.git"
 available: arch != "arm32" & arch != "x86_32" & arch != "ppc32" & arch != "ppc64"
 build: [
-  ["dune" "subst"] {pinned}
+  ["dune" "subst"] {dev}
   [
     "dune"
     "build"

packages/pbrt_services/pbrt_services.4.0/opam

@@ -14,7 +14,7 @@ depends: [
 ]
 dev-repo: "git+https://github.com/mransan/ocaml-protoc.git"
 build: [
-  ["dune" "subst"] {pinned}
+  ["dune" "subst"] {dev}
   [
     "dune"
     "build"

packages/pbrt_yojson/pbrt_yojson.4.0/opam

@@ -16,7 +16,7 @@ depends: [
 ]
 dev-repo: "git+https://github.com/mransan/ocaml-protoc.git"
 build: [
-  ["dune" "subst"] {pinned}
+  ["dune" "subst"] {dev}
   [
     "dune"
     "build"