meson: use include_type for nlohmann-json dependency

Using the include_type field aligns with usages in other repositories
and prevents the library from getting flagged by clang-tidy and similar
tools.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ie52cd2420138d44f55a0e8e997e26b61bd960812
diff --git a/meson.build b/meson.build
index c22163b..f22c893 100644
--- a/meson.build
+++ b/meson.build
@@ -41,7 +41,7 @@
   dependency('systemd'),
   dependency('sdbusplus'),
   dependency('phosphor-logging'),
-  dependency('nlohmann_json'),
+  dependency('nlohmann_json', include_type: 'system'),
 ]
 
 executable(