meson: add missing nlohmann dependencies to tests

Without it there are build failures because the include search path is
wrong in subproject mode.

Change-Id: I49ee9aab900a41ae91dccc43eccc68321f9d973a
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/common/test/meson.build b/common/test/meson.build
index 4c909c0..ad5700f 100644
--- a/common/test/meson.build
+++ b/common/test/meson.build
@@ -15,6 +15,7 @@
                          common_test_src,
                          gtest,
                          libpldm_dep,
+                         nlohmann_json,
                          phosphor_dbus_interfaces,
                          sdbusplus]),
        workdir: meson.current_source_dir())