add connection string to config

config/config.go

@@ -5,7 +5,8 @@ import (
 )
 
 type ServerConfig struct {
-	Port string
+	Port             string
+	ConnectionString string
 }
 
 type Config struct {
@@ -15,7 +16,8 @@ type Config struct {
 func New() *Config {
 	return &Config{
 		Server: ServerConfig{
-			Port: getEnv("PORT", ""),
+			Port:             getEnv("PORT", ""),
+			ConnectionString: getEnv("CONNECTION_STRING", "test.db"),
 		},
 	}
 }