Remove ts-jest warning when running tests

* This simple fix removes the annoying warning displayed below:
"ts-jest[config] (WARN) Unable to find the root of the project where ts-jest has been installed."

Signed-off-by: Alberto Diaz <alberto.diazdorado@tngtech.com>

frontend/jest.config.js

@@ -3,6 +3,7 @@ module.exports = {
   globals: {
     'ts-jest': {
       tsconfig: '<rootDir>/tsconfig-test.json',
+      packageJson: 'package.json',
     },
     API_URL: 'wss://api.url',
   },