change(mqtt): Update submodule to e6afdb

Update submodule:
git log --oneline
05b347643f6679cc60a50a9664b86a24ebf3ae10..e6afdb4025fe018ae0add44e3c45249ea1974774

Detailed description of the changes:
* fix: using return value of asprintf now
  - See merge request espressif/esp-mqtt!192
  - See commit https://github.com/espressif/esp-mqtt/commit/c0b40b1
* fix: Uses caps allocation for data buffer instead of item struct
  - See merge request espressif/esp-mqtt!193
  - See commit https://github.com/espressif/esp-mqtt/commit/00ee059

components/mqtt/esp-mqtt

@@ -1 +1 @@
-Subproject commit 05b347643f6679cc60a50a9664b86a24ebf3ae10
+Subproject commit e6afdb4025fe018ae0add44e3c45249ea1974774