Update changelog to include link to this PR

Author: jpolchlo

CHANGES.md

@@ -5,7 +5,7 @@
 ### Changed
 
 * Default branch to **main** ([#544](https://github.com/stac-utils/stac-fastapi/pull/544))
-* flake8 and isort replaced by ruff for pre-commit checks
+* flake8 and isort replaced by ruff for pre-commit checks ([#549](https://github.com/stac-utils/stac-fastapi/pull/549))
 
 ### Fixed