feat: Add "sub" claim for the openid scope

Required by OIDC clients like Gitea

handlers/user/info.go

@@ -57,6 +57,8 @@ func UserInfo(ctx *gin.Context) {
 		for _, s := range scopes {
 			if value, ok := (*userinfo)[s]; ok {
 				userinfoRes[s] = value
+			} else if s == "openid" {
+				userinfoRes["sub"] = *tokenInfo.Sub
 			}
 		}
 	}