build: fix dependency check for nlohmann/json

Fix the following error observed in Yocto bump:

    | Has header "nlomann/json.hpp" : NO
    |
    | ../git/meson.build:24:4: ERROR: Automatic wrap-based subproject downloading is disabled
    |

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I71a052f11d7d50c58ff5b16d124c54b636888f96
diff --git a/meson.build b/meson.build
index 6b21531..6a0b458 100644
--- a/meson.build
+++ b/meson.build
@@ -18,7 +18,7 @@
     )
 endif
 
-if cpp.has_header('nlomann/json.hpp')
+if cpp.has_header('nlohmann/json.hpp')
     nlohmann_json = declare_dependency()
 else
     subproject('nlohmann-json')