Fix output formatting in cairo-run

[Hopium21]

File changed: crates/bin/cairo-run/src/main.rs

Before: first = false; // After print!(", ")
After: first = false; // Before print!(", ")

This PR fixes the output formatting of panic messages in the Cairo runner by moving the first = false assignment before printing the comma separator. This ensures proper comma separation between panic values without an unnecessary leading comma.

[reviewable-StarkWare]

This change is 

[orizi]

Reviewed 2 of 2 files at r1.
Reviewable status: all files reviewed (commit messages unreviewed), 1 unresolved discussion (waiting on @Hopium21)

---

crates/bin/cairo-run/src/main.rs line 127 at r1 (raw file):

                    print!(", ");
                   }
                first = false;

run ./scripts/rust_fmt.sh

[Hopium21]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @Hopium21)