Re-format let-else per rustfmt update

compiler/rustc_span/src/lib.rs

@@ -2159,7 +2159,8 @@ where
         // If this is not an empty or invalid span, we want to hash the last
         // position that belongs to it, as opposed to hashing the first
         // position past it.
-        let Some((file, line_lo, col_lo, line_hi, col_hi)) = ctx.span_data_to_lines_and_cols(&span) else {
+        let Some((file, line_lo, col_lo, line_hi, col_hi)) = ctx.span_data_to_lines_and_cols(&span)
+        else {
             Hash::hash(&TAG_INVALID_SPAN, hasher);
             return;
         };