Don't fail if -u, -o or -a are not supplied for cve show command

[MrSeccubus]

Since the cve show command does not require a username it should not fail or prompt for an API key if none are supplied.

expected

$ cve show CVE-2024-27120
CVE-2024-27120
├─ State:	PUBLISHED
├─ Owning CNA:	DIVD
└─ Updated on:	Wed Aug 14 19:56:50 2024 +0000

reality

$ cve show CVE-2024-27120
Usage: cve [OPTIONS] COMMAND [ARGS]...
Try 'cve -h' for help.

Error: Missing option '-u' / '--username'.
$ cve -u unknown show CVE-2024-27120
Usage: cve [OPTIONS] COMMAND [ARGS]...
Try 'cve -h' for help.

Error: Missing option '-o' / '--org'
$  cve -u unknown -o unknonw show CVE-2024-27120
API key: ^C
Aborted!
$  cve -u unknown -o unknonw -a unknonw show CVE-2024-27120
CVE-2024-27120
├─ State:	PUBLISHED
├─ Owning CNA:	DIVD
└─ Updated on:	Wed Aug 14 19:56:50 2024 +0000

[mprpic]

Fixed! ping and show don't require auth credentials any more. Please test if you can; I'll release a new version to PyPI next week.