Server yarn test broken on fresh install

[Jérémie Pardou]

After a fresh install, if we try to execute the server side tests, we get this error:

yarn run v1.22.4
$ jest
 FAIL  src/utils/utils.test.js
  ● Test suite failed to run

    Requires Babel "^7.0.0-0", but was loaded with "6.26.3". If you are sure you have a compatible version of @babel/core, it is likely that something in your build process is loading the wrong version. Inspect the stack trace of this error to look for the first entry that doesn't mention "@babel/core" or "babel-core" to see what is calling Babel.
      
      at throwVersionError (node_modules/@babel/helper-plugin-utils/lib/index.js:65:11)
      at Object.assertVersion (node_modules/@babel/helper-plugin-utils/lib/index.js:13:11)
      at node_modules/@babel/plugin-transform-async-to-generator/lib/index.js:51:7
      at node_modules/@babel/helper-plugin-utils/lib/index.js:19:12
      at Function.memoisePluginContainer (node_modules/babel-core/lib/transformation/file/options/option-manager.js:113:13)
      at Function.normalisePlugin (node_modules/babel-core/lib/transformation/file/options/option-manager.js:146:32)
      at node_modules/babel-core/lib/transformation/file/options/option-manager.js:184:30
          at Array.map (<anonymous>)
      at Function.normalisePlugins (node_modules/babel-core/lib/transformation/file/options/option-manager.js:158:20)
      at OptionManager.mergeOptions (node_modules/babel-core/lib/transformation/file/options/option-manager.js:234:36)
      at OptionManager.init (node_modules/babel-core/lib/transformation/file/options/option-manager.js:368:12)
      at File.initOptions (node_modules/babel-core/lib/transformation/file/index.js:212:65)
      at new File (node_modules/babel-core/lib/transformation/file/index.js:135:24)
      at Pipeline.transform (node_modules/babel-core/lib/transformation/pipeline.js:46:16)
          at Generator.next (<anonymous>)
          at new Promise (<anonymous>)

Test Suites: 1 failed, 1 total
Tests:       0 total
Snapshots:   0 total
Time:        1.473s
Ran all test suites.
error Command failed with exit code 1.