deps: bump the sylpheed-formats pin 47f423f -> b436e5a for the rest() fix

What I wanted from it: `ui_layout::rest()`. At 47f423f a trailing run of
identical keyframes was always treated as the exit, so an element with no exit
animation rested at its invisible pre-roll -- `ptframe1`/`ptframe2`, the main
menu's circuit bracket, which a capture of the running game plainly shows.

Pinned at b436e5a rather than 5e6cf0d where the fix was written, because
b436e5a is where it carries its disc-wide check: 30 of 13 991 elements move, 4
become visible, 0 become invisible. The rule shipped is the RE agent's, not the
condition this port proposed -- mine was too loose and would have erased the
word PAUSE on `pgptitle.rat`, whose trailing run is two identical TRANSPARENT
frames. A trailing run is the hold exactly when it is VISIBLE.

The re-export shows the change was contained: two files differ, and within them
exactly four `rest` blocks -- ptframe1/ptframe2 on both main menus, t=16 alpha
0x00 at the pre-roll position becoming t=62 alpha 0xff at the arrived one.
Every diff line pairs. The other ten screens are byte-identical, no sprite
changed, and `pteff02` correctly did not move.

Cargo.lock

@@ -959,7 +959,7 @@ dependencies = [
 [[package]]
 name = "sylpheed-formats"
 version = "0.1.0"
-source = "git+https://git.mc02.dev/fabi/Syplheed-Reborn.git?rev=8b6dbcf#8b6dbcfead4168a674015f0e4fd2c8d83f9ffe31"
+source = "git+https://git.mc02.dev/fabi/Syplheed-Reborn.git?rev=5414db3#5414db34bfc0d0b0743e07e6e89f345540dc2e94"
 dependencies = [
  "anyhow",
  "binrw",