Gitea: Internal API HTTP client hardcodes InsecureSkipVerify:true with no config override

Summary Gitea's internal API HTTP client modules/private/internal.go hardcodes TLSClientConfig.InsecureSkipVerify = true with no configuration override. It is the only outbound TLS client in the codebase that cannot be made to verify its peer's certificate — webhook, migrations, MinIO, LDAP, SMTP...