CHANGELOG updates for 8.13.0 (#9408)

* 8.13 CHANGELOGs

* Remove trailing whitespace

* Remove trailing whitespace

Crashlytics/CHANGELOG.md

@@ -1,4 +1,4 @@
-# Unreleased
+# v8.13.0
 - [added] Updated upload-symbols to 3.11 and added logic to process Flutter project information (#9379)
 - [fixed] Added native support for ARM / M1 Macs in upload-symbols (#8965)
 - [fixed] Fixed an issue where passing nil as a value for a custom key or user ID did not clear the stored value as expected.

FirebasePerformance/CHANGELOG.md

@@ -1,4 +1,4 @@
-# Unreleased
+# Version 8.13.0
 * [fixed] Make pre-warming identification more reliable by moving the pre-warm check to the earliest phase of app start.
 
 # Version 8.12.0