Updating Gin and JWT causes a regression and an error message

1. Updating from Gin 1.6.2 to Gin v1.4.7 in go.mod causes a regression (impossible to register a modified content in a page).

See 1e837963

TODO: Debug and fix this so one can use the latest version of gin.

2. Updating JWT URL from github.com/dgrijalva/jwt-go to github.com/golang-jwt/jwt displays an error when using go run main.go.

See jwt.go and go.mod:

TODO: Debug and fix this so one can use github.com/golang-jwt/jwt.