Fix spelling in changelog

Author: jackc

CHANGELOG.md

@@ -3,7 +3,7 @@
 Use spaces instead of parentheses for SQL sanitization.
 
 This still solves the problem of negative numbers creating a line comment, but this avoids breaking edge cases such as
-`set foo to $1` where the substition is taking place in a location where an arbitrary expression is not allowed.
+`set foo to $1` where the substitution is taking place in a location where an arbitrary expression is not allowed.
 
 # 5.5.4 (March 4, 2024)