Fix compile error on macOS

[BrettDong]

Summary

None

Purpose of change

#54693 breaks macOS build:

Error: src/widget.cpp:395:31: error: loop variable 'val' is always a copy because the range of type 'JsonArray' does not return a reference [-Werror,-Wrange-loop-analysis]
        for( const JsonValue &val : jo.get_array( "bodyparts" ) ) {
                              ^
src/widget.cpp:395:14: note: use non-reference type 'JsonValue'
        for( const JsonValue &val : jo.get_array( "bodyparts" ) ) {
             ^~~~~~~~~~~~~~~~~~~~~~
1 error generated.
make: *** [obj/tiles/widget.o] Error 1

Describe the solution

Change reference to value.

Describe alternatives you've considered

Testing

Additional context

[dseguin]

Thanks!