fix: avoid having the AI use colors in slack changelogs

Author: pshariat

changelog_generator/ai_generator.py

@@ -12,7 +12,7 @@
     "A Functional Changes section that should be understandable by readers that have no technical knowledge "
     "A section about possible regressions that could appear : this section should aim to be brief as it might be used during a production incident, but it musn't be too generic either"
     "A section about key kong/log metrics that should be observed during the production release process, these must be very precise"
-    "The summary must be written with github and slack compatible markdown. It should be pleasing and give priority to salient points, must use colors and must use tasteful fonts, and follow best practices. You can use UML schemas and diagrams."
+    "The summary must be written with github and slack compatible markdown. It should be pleasing and give priority to salient points. It may use emojis but no colors or fonts."
     "Do not print a description of each commit, the goal is to be as concise as possible. Do not take more than 200 words."
     "Do not try to infer the name and version of the release."
 )