jws: jwt.go - added "typ":"JWT" to protected header.

jws/jwt.go

diff --git a/jws/jwt.go b/jws/jwt.go
index 08e8301..c8f7a69 100644
--- a/jws/jwt.go
+++ b/jws/jwt.go
@@ -10,6 +10,7 @@
 // NewJWT creates a new JWT with the given claims.
 func NewJWT(claims Claims, method crypto.SigningMethod) jwt.JWT {
 	j := New(claims, method).(*jws)
+	j.sb[0].protected.Set("typ", "JWT")
 	j.isJWT = true
 	return j
 }