Move a space into the diamond flag string

[Uwuewsky]

Summary

None

Purpose of change

Recently it became possible to change the position of components in tname, but the space added by the code made it a bit more difficult: "diamond" + " "

Describe the solution

Move that space into the string itself: "diamond "

Describe alternatives you've considered

Testing

Haven't tested due to my inability to do so, but the exact same operation of adding pgettext with std::string is shown in:

Cataclysm-DDA/src/item_tname.cpp

Line 408 in c2fdece

ret += pgettext( "The radio mod is associated with the [R]ed button.", "R)" );

Additional context