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/test/meson.build b/test/meson.build
index 3a85b08..5002167 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -6,7 +6,7 @@
 test_deps=[
     gmock_dep,
     gtest_dep,
-    json_dep,
+    nlohmann_json_dep,
     phosphor_dbus_interfaces_dep,
     phosphor_logging_dep,
     sdbusplus_dep