Add missing f-string and update bool pattern for manual saves

[DrymarchonShaun]

133c81c fixes some backup files having the literal suffix BAK{int(time.time())}

7c280b0 will probably fix #4; Autosaves have 2 bytes following "Bool", manual saves only have 1:

placeholder file names, since the actual ones are insanely long

hexdiff autosave.sav  autosave.sav.BAK1746820773
   offset      0 1 2 3 4 5 6 7 01234567       offset      0 1 2 3 4 5 6 7 01234567
0x0000000000  4756415303000000 GVAS....    0x0000000000  4756415303000000 GVAS....
...
0x00000a3d18  6f6f6c0000436861 ool..Cha    0x00000a3d18  6f6f6c0001436861 ool..Cha
0x00000a3d20  7261637449641005 ractId..    0x00000a3d20  7261637449641005 ractId..
...

hexdiff manual_save.sav manual_save.sav.BAK1746821838
   offset      0 1 2 3 4 5 6 7 01234567       offset      0 1 2 3 4 5 6 7 01234567
0x0000000000  4756415303000000 GVAS....    0x0000000000  4756415303000000 GVAS....
...
0x00000a31c0  426f6f6c00436861 Bool.Cha    0x00000a31c0  426f6f6c01436861 Bool.Cha
0x00000a31c8  7261637449641005 ractId..    0x00000a31c8  7261637449641005 ractId..
...

[NullDev]

Thank you!