Update CHANGELOG.md

Fixes for #222

- Update for MQ 9.4.2

- ibmmq - Add function to map PCF attribute values to strings
- ibmmq - Interpret more PCF types (the filters)
- ibmmq - MaxSCOLength fix - PR #216
- ibmmq - Add MQIGolangVersion function
- ibmmq - Handle MQ C client callbacks with wrong hObj (#217)
- mqmetric - Ignore the EXTENDED queue metrics unless explicitly enabled
- mqmetric - Deal with possible duplication of metrics between QSTATUS and published QSTAT values
  Without this change, Prometheus (at least) will panic. The system topic metrics were extended
  in MQ 9.4.2 and potentially in various fixpacks for older LTS releases; this version of the collector code is required
  once you reach those qmgr levels.
- mqmetric - Recognise Native HA Cross-region replication metrics
- ibmmqotel - Fix concurrent maps (#218)
- samples - Modify amqspcf.go to use PCF mapping functions
- samples - Ensure Dockerfile examples do not pull base images from Dockerhub
- samples - Remove unnecessary (incorrect) declarations

Final 9.4.1 updates

Update for MQ 9.4.0.0

Update for MQ 9.3.5

mqmetric - MQ93 enables reformatted subscriptions for resource metrics

mqmetric - handle empty QueueSubFilter options

Update for MQ 9.3.4

- ibmmq - Support for new CSP JWT Token field

Update for MQ 9.3.3