stick to jwt-go v2

[bamarni]

I was getting :

# github.com/alternaDev/go-firebase-verify
../../../github.com/alternaDev/go-firebase-verify/verify.go:50: invalid operation: parsedToken.Claims["aud"] (type jwt.Claims does not support indexing)
../../../github.com/alternaDev/go-firebase-verify/verify.go:51: invalid operation: parsedToken.Claims["aud"] (type jwt.Claims does not support indexing)
../../../github.com/alternaDev/go-firebase-verify/verify.go:52: invalid operation: parsedToken.Claims["iss"] (type jwt.Claims does not support indexing)
../../../github.com/alternaDev/go-firebase-verify/verify.go:54: invalid operation: parsedToken.Claims["sub"] (type jwt.Claims does not support indexing)
../../../github.com/alternaDev/go-firebase-verify/verify.go:62: invalid operation: parsedToken.Claims["sub"] (type jwt.Claims does not support indexing)

Instructions for upgrading to v3 are here : https://github.com/dgrijalva/jwt-go/blob/master/MIGRATION_GUIDE.md

But until then it can still be pinned to v2 using gopkg.in 😃

[bamarni]

or... #4