Restrict mariadb

Upstream fix: ocaml-community/ocaml-mariadb#49

Author: emillon

packages/mariadb/mariadb.1.1.5/opam

@@ -17,7 +17,7 @@ depends: [
   "ocaml" {>= "4.07.0" & < "5.0"}
   "ocamlfind" {build}
   "ocamlbuild" {build}
-  "ctypes" {>= "0.7.0"}
+  "ctypes" {>= "0.7.0" & < "0.21.0"}
   "conf-mariadb"
   "conf-gcc"
 ]

packages/mariadb/mariadb.1.1.6/opam

@@ -17,7 +17,7 @@ depends: [
   "ocaml" {>= "4.07.0" & < "5.0"}
   "ocamlfind" {build}
   "ocamlbuild" {build}
-  "ctypes" {>= "0.7.0"}
+  "ctypes" {>= "0.7.0" & < "0.21.0"}
   "conf-mariadb"
   "conf-gcc"
 ]