Fix intermittent Cancelled tests failure

- Fixed:
  - Fix `Cancelled` test failures:  
    The intermittent test failures which output "Cancelled" in failure stack trace.  
    More like a hack at this point but adding `Sleep` in test initialisation function seems to fixes this issue. Looks like VSCode + extension(s) need some time to initialise properly but I could not find any suitable event for that to wait for instead. 
  - Fix `CHANGELOG` formatting  
    Minor fix of the previous release

CHANGELOG.md

@@ -1,9 +1,15 @@
 # Change Log
 All notable changes to the "Haskutil" extension will be documented in this file.
 
+## [0.13.1] - 2024-05-11
+### Fixed
+* Intermittent test failures  
+  Failures with "Cancelled" error message
+* CHANELOG formatting
+
 ## [0.13.0] - 2024-05-07
 ### Added
-* [Purple Yolk](https://github.com/tfausak/purple-yolk) extension is added to the list of `haskutil.supportedDependencies`
+* [Purple Yolk](https://github.com/tfausak/purple-yolk) extension is added to the list of `haskutil.supportedDependencies`  
   ([#73](https://github.com/EduardSergeev/vscode-haskutil/pull/73) - thanks to [Taylor Fausak](https://github.com/tfausak) for contribution)
 ### Fixed
 * CI build on MacOS