update travis and minimum ocaml version

Author: avsm

.travis.yml

@@ -7,9 +7,9 @@ env:
     - PINS="ezjsonm:."
     - PACKAGE=ezjsonm-lwt
   matrix:
-    - OCAML_VERSION=4.03
     - OCAML_VERSION=4.04
+    - OCAML_VERSION=4.05
     - OCAML_VERSION=4.06
-    - OCAML_VERSION=4.07
+    - OCAML_VERSION=4.10
 os:
   - linux

ezjsonm.opam

@@ -7,7 +7,7 @@ homepage: "https://github.com/mirage/ezjsonm"
 doc: "https://mirage.github.io/ezjsonm/"
 bug-reports: "https://github.com/mirage/ezjsonm/issues"
 depends: [
-  "ocaml" {>="4.03.0"}
+  "ocaml" {>="4.04.0"}
   "dune" {>= "2.0"}
   "alcotest" {with-test & >= "0.4.0"}
   "jsonm" {>= "1.0.0"}