fix(main.tf): supply curated list of special chars

[vdice]

• Curates a specific list of special chars for use in the hippo password

Motivated by cases like the following:

$ printf $HIPPO_PASSWORD | pbcopy
-bash: printf: `[': invalid format character

[lann]

$ printf $HIPPO_PASSWORD | pbcopy

or: $ echo -n "$HIPPO_PASSWORD" | pbcopy

[lann]

$ printf $HIPPO_PASSWORD | pbcopy

or: $ echo -n "$HIPPO_PASSWORD" | pbcopy ?

[vdice]

or: $ echo -n "$HIPPO_PASSWORD" | pbcopy ?

Thanks, yup, I did switch to an echo approach as well... but... still wanted to unblock a known technique.