Updated CHANGELOG.md to include recent enhancements

- Integrated OAuth for secure Slack deployment notifications Issue 194.
- Streamlined build and deployment process for faster CD and reduced
  resource use Issue 246.

CHANGELOG.md

@@ -33,6 +33,8 @@ changes.
 - Renamed project from VVA to GovTool [Issue 97](https://github.com/IntersectMBO/govtool/issues/97).
 - (`docs/update-working-conventions`) Addressing [Issue 25](https://github.com/IntersectMBO/govtool/issues/25) changed working conventions documentation to improve intended flows.
 - Adjusted Nix configuration to meet projects needs [Issue 187](https://github.com/IntersectMBO/govtool/issues/187).
+- Integrated OAuth to securely notify about deployment status in Slack [Issue 194](https://github.com/IntersectMBO/govtool/issues/194).
+- Streamlined the application build and deployment process, thereby accelerating continuous delivery (CD) and reducing the resource burden [Issue 246](https://github.com/IntersectMBO/govtool/issues/246).
 
 ### Removed
 -