add flag to exclude specific tags

[jrdn91]

Feature description

The flag that allows to only include certain tags is great, but I have a couple usecases so far that something like an -exclude-tags= flag would be awesome.

Why would it be useful?

Specifically, we have a DATABASE_URL env variable we use to connect our ORM to the database. Locally this should be a local server running, which can be overridden. But there are some instances, such as running migrations against other databases, that being able to quickly comment and un-comment a variable in a local .env file would be quicker and easier than using the override. If I could add a tag of some kind to the DATABASE_URL env and subsequently exclude only that tagged env variable when running locally I could then fallback to the local .env file when running our app locally

Additional context

Additionally, a mechanism to allow for a local .env override would be really nice as well which would solve the same usecase.