meson: adjust nlohmann-json dependency

- Simplify the dependency logic in the meson.build.
- Align the meson dep name with consistent practices from other repos.
- Use the non-versioned wrap file.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I0e3052763bffe9f98d8ca10c5b523b58e000f636
diff --git a/monitor/meson.build b/monitor/meson.build
index 1171530..1fa26b8 100644
--- a/monitor/meson.build
+++ b/monitor/meson.build
@@ -17,7 +17,7 @@
 ]
 
 deps=[
-    json_dep,
+    nlohmann_json_dep,
     phosphor_dbus_interfaces_dep,
     phosphor_logging_dep,
     sdbusplus_dep,