fix(*.opam): Add missing deps for server/client build in isolation

Author: erikmd

learn-ocaml-client.opam

@@ -35,6 +35,7 @@ depends: [
   "ocp-ocamlres" {>= "0.4"}
   "omd" {<= "1.3.1"}
   "ppx_fields_conv"
+  "ppxlib"
   "ppx_sexp_conv"
   "ppx_tools"
   "ssl" {= "0.5.5"}

learn-ocaml.opam

@@ -50,7 +50,10 @@ depends: [
   "omd" {<= "1.3.1"}
   "pprint"
   "ppx_cstruct"
+  "ppxlib"
+  "ppx_sexp_conv"
   "ppx_tools"
+  "ppx_tools_versioned"
   "re"
   "ssl" {= "0.5.5"}
   "uutf" {>= "1.0" }