chore(sources/env): bump gosettings to v0.3.0-rc13

- Use `RetroKeys` option with env.* method calls
- Use `CSV*` typed methods
- Inject `handleDeprecatedKey` function

internal/configuration/sources/env/helpers.go

@@ -3,6 +3,8 @@ package env
 import (
 	"fmt"
 	"os"
+
+	"github.com/qdm12/gosettings/sources/env"
 )
 
 func unsetEnvKeys(envKeys []string, err error) (newErr error) {
@@ -19,3 +21,13 @@ func unsetEnvKeys(envKeys []string, err error) (newErr error) {
 func ptrTo[T any](value T) *T {
 	return &value
 }
+
+func firstKeySet(e env.Env, keys ...string) (firstKeySet string) {
+	for _, key := range keys {
+		value := e.Get(key)
+		if value != nil {
+			return key
+		}
+	}
+	return ""
+}