Wrong program name printed by `bz3grep`

[dearblue]

For example, if I use only the -A switch, an error is printed, but the program name, which has nothing to do with "bzip3", is printed.

% bz3grep -A
zstdgrep: missing argument for -A flag

Since the current bzip3 has no equivalent to bzegrep and bzfgrep, one solution would be to remove the decision block itself.

https://github.com/kspalaiologos/bzip3/blob/1.4.0/bz3grep#L38-L43

[Kamila Szewczyk]

Thanks, fixed.