Tiny formatting fix in AS change log [ci skip]

activesupport/CHANGELOG.md

@@ -2,10 +2,10 @@
 
     Replacements:
 
-       5.ago   => 5.seconds.ago
-       5.until => 5.seconds.until
-       5.since => 5.seconds.since
-       5.from_now => 5.seconds.from_now
+        5.ago   => 5.seconds.ago
+        5.until => 5.seconds.until
+        5.since => 5.seconds.since
+        5.from_now => 5.seconds.from_now
 
     See #12389 for the history and rationale behind this.