Set minimum ocaml version to 4.08

Author: andersfugmann

Changelog

@@ -9,6 +9,8 @@ Changes marked with '*' indicates a changes that breaks backward compatibility
 [ ] Add namespaces to attributes
 [ ] Unify xmlm and xml_light driver to share codebase
 
+5.2.1
+[x] Set minimum ocaml version to 4.08
 [x] Remove warnings on using kprintf and switch to reference Stdlib and not Caml
 [x] Require yojson >= 1.6.0 and remove upper constraint on yojson
 [x] Fix package description for yaml driver

ppx_protocol_conv_json.opam

@@ -11,7 +11,7 @@ build: [
   ["dune" "runtest" "-p" name "-j" jobs] {with-test}
 ]
 depends: [
-  "ocaml" {>= "4.04.0"}
+  "ocaml" {>= "4.08"}
   "ppx_protocol_conv" {= version}
   "yojson" {>= "1.6.0"}
   "dune" {>= "1.2"}

ppx_protocol_conv_jsonm.opam

@@ -11,7 +11,7 @@ build: [
   ["dune" "runtest" "-p" name "-j" jobs] {with-test}
 ]
 depends: [
-  "ocaml" {>= "4.04"}
+  "ocaml" {>= "4.08"}
   "ppx_protocol_conv" {= version}
   "ezjsonm"
   "dune" {>= "1.2"}

ppx_protocol_conv_msgpack.opam

@@ -11,7 +11,7 @@ build: [
   ["dune" "runtest" "-p" name "-j" jobs] {with-test}
 ]
 depends: [
-  "ocaml" {>= "4.04.0"}
+  "ocaml" {>= "4.08"}
   "ppx_protocol_conv" {= version}
   "msgpck" {>= "1.3"}
   "msgpck" {with-test & >= "1.7"}

ppx_protocol_conv_xml_light.opam

@@ -11,7 +11,7 @@ build: [
   ["dune" "runtest" "-p" name "-j" jobs] {with-test}
 ]
 depends: [
-  "ocaml" {>= "4.04.0"}
+  "ocaml" {>= "4.08"}
   "ppx_protocol_conv" {= version}
   "xml-light"
   "dune" {>= "1.2"}

ppx_protocol_conv_xmlm.opam

@@ -11,7 +11,7 @@ build: [
   ["dune" "runtest" "-p" name "-j" jobs] {with-test}
 ]
 depends: [
-  "ocaml" {>= "4.04"}
+  "ocaml" {>= "4.08"}
   "ppx_protocol_conv" {= version}
   "ezxmlm"
   "dune" {>= "1.2"}

ppx_protocol_conv_yaml.opam

@@ -11,7 +11,7 @@ build: [
   ["dune" "runtest" "-p" name "-j" jobs] {with-test}
 ]
 depends: [
-  "ocaml" {>= "4.04.0"}
+  "ocaml" {>= "4.08"}
   "dune" {>= "1.2"}
   "ppx_protocol_conv" {= version}
   "yaml" { >= "2.0.0"}