Update docker.io/eclipse-mosquitto Docker tag to v2.0.21
No problems deploying Eclipse Mosquitto patch version to Proxmox VE K3s Kubernetes cluster via Flux V2 image reconciliation in a GitOps approach with dependency update facilitated by Mend's Renovate Bot.
This MR contains the following updates:
| Package | Update | Change | 
|---|---|---|
| docker.io/eclipse-mosquitto | patch | 2.0.20->2.0.21 | 
Release Notes
eclipse/mosquitto (docker.io/eclipse-mosquitto)
v2.0.21
===================
Security:
- Fix leak on malicious SUBSCRIBE by authenticated client.
 Closes eclipse #248.
- Further fix for CVE-2023-28366.
Broker:
- Fix clients sending a RESERVED packet not being quickly disconnected.
 Closes #2325.
- Fix bind_interfaceproducing an error when used with an interface that has
 an IPv6 link-local address and no other IPv6 addresses. Closes #2696.
- Fix mismatched wrapped/unwrapped memory alloc/free in properties. Closes #3192.
- Fix allow_anonymous falsenot being applied in local only mode. Closes #3198.
- Add retain_expiry_intervaloption to fix expired retained message not
 being removed from memory if they are not subscribed to. Closes #3221.
- Produce an error if invalid combinations of cafile/capath/certfile/keyfile
 are used. Closes #1836. Closes #3130.
- Backport keepalive checking from develop to fix problems in current
 implementation. Closes #3138.
Client library:
- Fix potential deadlock in mosquitto_sub if -Wis used. Closes #3175.
Apps:
- mosquitto_ctrl dynsec now also allows -ito specify a clientid as well as
 -c. This matches the documentation which states-i. Closes #3219.
 Client library:
- Fix threads linking on Windows for static libmosquitto library
 Closes #3143
Build:
- Fix Windows builds not having websockets enabled.
- Add tzdata to docker images
Tests:
- Fix 08-ssl-connect-cert-auth-expired and 08-ssl-connect-cert-auth-revoked
 tests when under load. Closes #3208.
