test: improve type safety in customUpdater test

- Replaced `any` with `unknown` for type safety.

Author: taj54

dist/index.js

@@ -6,7 +6,7 @@
  * Author: Taj <[email protected]>
  * Homepage: https://github.com/taj54/universal-version-bump#readme
  * License: MIT
- * Generated on Fri, 29 Aug 2025 19:02:47 GMT
+ * Generated on Fri, 29 Aug 2025 19:18:30 GMT
  */
 require('./sourcemap-register.js');/******/ (() => { // webpackBootstrap
 /******/ 	var __webpack_modules__ = ({

tests/updaters/customUpdater.test.ts

@@ -21,8 +21,8 @@ describe('CustomUpdater', () => {
     customUpdater = new CustomUpdater(filePath, variableName);
 
     // Mock the constructor's internal assignments
-    (customUpdater as any).fileHandler = mockFileHandler;
-    (customUpdater as any).manifestParser = mockManifestParser;
+    (customUpdater as unknown).fileHandler = mockFileHandler;
+    (customUpdater as unknown).manifestParser = mockManifestParser;
   });
 
   it('should always return true for canHandle', () => {