Error after ugpgrade to v1.17.1

[avrekhm]

Hi!
After the recent upgrade to v1.17.1, builds are failing with this error:

encode.go:1260:12: sf.IsExported undefined (type reflect.StructField has no field or method IsExported)

Confirmed with go1.14.15 and go1.16.5.

[JonasAlfredsson]

You will need GO > 1.17 for this to work from now on.
The reflect package has been updated to include this new function, so the mod file in this repo should probably be updated to reflect (pun intended) this.

[JonasAlfredsson]

I had to go back to

go get github.com/clarketm/json@v1.15.7

for it to work for me with GO 1.16.4

[Splizard]

This should be documented in the go.mod

[Splizard]

#6