chore: replace dotenv with dotenvy, a slightly more maintained version of the same library (#50)

Reviewed-on: https://git.front.kjuulh.io/kjuulh/gitnow/pulls/50
Co-authored-by: kjuulh <contact@kjuulh.io>
Co-committed-by: kjuulh <contact@kjuulh.io>

crates/gitnow/Cargo.toml

@@ -17,7 +17,7 @@ tokio.workspace = true
 tracing.workspace = true
 tracing-subscriber.workspace = true
 clap.workspace = true
-dotenv.workspace = true
+dotenvy.workspace = true
 
 serde = { version = "1.0.197", features = ["derive"] }
 uuid = { version = "1.7.0", features = ["v4"] }