Upgrade json-jwt to v1.11.0

This fixes CVE-2019-18848 and brings in a number of minor fixes:
https://github.com/nov/json-jwt/compare/v1.9.4..v1.11.0

Closes https://gitlab.com/gitlab-org/gitlab/issues/39148

Gemfile.lock

@@ -532,8 +532,8 @@ GEM
       regexp_parser (~> 1.1)
       regexp_property_values (~> 0.3)
     json (1.8.6)
-    json-jwt (1.9.4)
-      activesupport
+    json-jwt (1.11.0)
+      activesupport (>= 4.2)
       aes_key_wrap
       bindata
     json-schema (2.8.0)

changelogs/unreleased/sh-bump-json-jwt.yml

+---
+title: Upgrade json-jwt to v1.11.0
+merge_request: 22440
+author:
+type: security