feat: Disable logging in release build

[Pscheidl]

If this crate is used in a production environment with trace/debug logging level enabled, it prints out all secrets stored in envrionment variables to the logs. As most projects don't need environment variable logging at all, the logging feature is hidden behind a feature flag, completely avoiding runtime checks.

[Pscheidl]

Having to opt-in for logging is a breaking change, but arguably is the most common use case ?

[Xuanwo]

Nice catch, lib like serde-env should not print any log to users. We can use log's native feature to implement this, like:

[dependencies]
log = { version = "0.4", features = ["max_level_trace", "release_max_level_off"] }

reference: https://docs.rs/log/latest/log/#compile-time-filters

[Pscheidl]

Nice catch, lib like serde-env should not print any log to users. We can use log's native feature to implement this, like:

[dependencies]
log = { version = "0.4", features = ["max_level_trace", "release_max_level_off"] }

reference: https://docs.rs/log/latest/log/#compile-time-filters

That's very convenient, thanks. Made the changes. No point in opting in/out then.

[Xuanwo]

Thanks for your PR!