Preserve spaces around interpolated expressions in format strings, in user-defined functions

[muzimuzhi]

When formatting a justfile containing user-defined functions which uses format strings in function bodies and arguments, the spaces around interpolated expressions in format strings were removed.

But in (almost?) all other places, such spaces are preserved.

set unstable

info(msg) := f"{{ BOLD + BLUE + msg + NORMAL }}"

echo:
    echo {{ info(f"{{ justfile() }}") }}
    echo {{ justfile() }}
    echo f"{{ justfile() }}"

just --fmt --check then gives

 set unstable

-info(msg) := f"{{ BOLD + BLUE + msg + NORMAL }}"
+info(msg) := f"{{BOLD + BLUE + msg + NORMAL}}"

 echo:
-    echo {{ info(f"{{ justfile() }}") }}
+    echo {{ info(f"{{justfile()}}") }}
     echo {{ justfile() }}
     echo f"{{ justfile() }}"
error: Formatted justfile differs from original.

$ just --version
just 1.50.0

[casey]

Good catch, I think we should definitely fix this. However, changing formatting might break CI jobs or other uses of just --fmt --check. Formatting changed recently, in I'd like to keep these changes infrequent, so I might wait for a bit in the hopes that I can batch this change with others.