When decompressing with `--format`, don't overwrite input

[marcospb19]

When using the --format flag, Ouch will decompress the output while overwriting the input file.

 $ touch file                           
 $ ouch compress file file.zst.zst.zst
[INFO] Successfully compressed 'file.zst.zst.zst'.
 $ ouch decompress file.zst.zst.zst --format zst   
Do you want to overwrite './file.zst.zst.zst'? [Y/n] 
...

It would be good to decompress the file without erasing the previous data.