Remove production check around baseUrl allowlist before 1.0.0

[blaine-arcjet]

In #83, we added an allowlist check for the ARCJET_BASE_URL environment variable; however, validation is only done in when process.env["NODE_ENV"] === "production" to allow for experimentation in non-production environments.

Before we hit 1.0.0, we want to remove this conditional. Users will still be able to use baseUrls not on the allowlist via custom clients.

[blaine-arcjet]

@davidmytton with my comment at #932 (comment), do you want to delay this further or do it before beta?

[davidmytton]

Let's do it before 1.0.0 and delay it for beta. Using the env var is easier for us :)