fix changelog [ci skip]

Author: metagn

changelog.md

@@ -54,7 +54,6 @@
   ```
 - [Case statement macros](manual.html#macros-case-statement-macros) are no longer experimental,
   meaning you no longer need to enable the experimental switch `caseStmtMacros` to use them.
-  meaning you no longer need to enable the experimental switch `caseStmtMacros` to use them. 
 - Full command syntax and block arguments i.e. `foo a, b: c` are now allowed
   for the right-hand side of type definitions in type sections. Previously
   they would error with "invalid indentation".