fix: change the default charset value

.env.example

@@ -12,7 +12,7 @@ DB_HOST=mysql
 DB_USER=bigcapital
 DB_PASSWORD=bigcapital
 DB_ROOT_PASSWORD=root
-DB_CHARSET=utf-8
+DB_CHARSET=utf8
 
 # System database
 SYSTEM_DB_NAME=bigcapital_system
@@ -46,4 +46,4 @@ AGENDASH_AUTH_PASSWORD=123123
 # Sign-up restrictions
 SIGNUP_DISABLED=true
 SIGNUP_ALLOWED_DOMAINS=
-SIGNUP_ALLOWED_EMAILS=
+SIGNUP_ALLOWED_EMAILS=