Dotenv output is not compatible with Ruby Dotenv

Hi.
Ruby Dotenv >=3  deprecated this format for environment variable values
```
PRIVATE_KEY="-----BEGIN RSA PRIVATE KEY-----\nHkVN9...\n-----END DSA PRIVATE KEY-----\n"
```

and requires use of multi-line values

```
PRIVATE_KEY="-----BEGIN RSA PRIVATE KEY-----
...
HkVN9...
...
-----END DSA PRIVATE KEY-----"
``` 

ref: https://github.com/bkeepers/dotenv?tab=readme-ov-file#multi-line-values

