Fix bug where JSON-initialized claims don't emit proper B64 when stringified.

src/main/jwt_full/claims.nim

@@ -59,7 +59,7 @@ proc initJwtClaims*(n: JsonNode): JwtClaims =
   ## Create a JwtClaims from a given set of claims as a JsonNOde
 
   return JwtClaims(
-    rawB64: $n,
+    rawB64: b64UrlEncode($n),
     json: n,
     iss: n.optStrVal("iss"),
     sub: n.optStrVal("sub"),