chore: Update tfsec install to include new URL and fix grep

[margaritakop]

This change is to:

1. reflect the recent acquisition of tfsec by aquasec that resulted in a url change for the installation source
2. update the grep command that now returns two results, hence the fix to select 1 (-m 1)

[andormarkus]

Hi @margaritakop

Please can you update the Dockerfile as well?

Thanks,
Andor

[margaritakop]

Hi @andormarkus, See the command in the dockerfile updated too.

[MaxymVlasov]

Wow, cool grep option. I will replace the recently merged | head -n 1 on -m 1.

Thank you for participate!