General: Bump json to 2.21.2 in the fastlane bundle

json 2.20.0 through 2.21.1 leave the resumable parser's state pointers
dangling after cResumableParser_parse releases the input buffer, so a
later partial_value call on a truncated object with duplicate keys reads
freed memory and can abort the process.

Nothing in the fastlane bundle constructs a JSON::ResumableParser, and
this lockfile is only consumed by the release workflow talking to Google
Play, so the vulnerable path is unreachable here. Bumping anyway because
it is a single-line patch bump that clears the alert.

Regenerated with `bundle lock --update=json`; no other gem moved.

Author: d4rken

fastlane/Gemfile.lock

@@ -173,7 +173,7 @@ GEM
     httpclient (2.9.0)
       mutex_m
     jmespath (1.6.2)
-    json (2.21.1)
+    json (2.21.2)
     jwt (3.2.0)
       base64
     logger (1.7.0)