chore(@redux-devtools/app): fix lint error

Error message:

0:0  error  Parsing error: "parserOptions.project" has been set for @typescript-eslint/parser.
The file does not match your project config: test/__mocks__/styleMock.ts.
The file must be included in at least one of the projects provided

packages/redux-devtools-app/jest.config.js

@@ -3,6 +3,6 @@ module.exports = {
   setupFilesAfterEnv: ['<rootDir>/test/setup.ts'],
   testEnvironment: 'jsdom',
   moduleNameMapper: {
-    '\\.css$': '<rootDir>/test/__mocks__/styleMock.ts',
+    '\\.css$': '<rootDir>/test/__mocks__/styleMock.js',
   },
 };

packages/redux-devtools-app/test/__mocks__/styleMock.js

@@ -0,0 +1 @@
+module.exports = {};

packages/redux-devtools-app/test/__mocks__/styleMock.ts

@@ -1 +0,0 @@
-export default {};