Jest: Fix jest-haste-map warning

Tell Jest to ignore package.json files in tests/build/ and in the
cypress/ folder. Otherwise, it prints out a warning about duplicate
names used in package.json.

Example:
jest-haste-map: Haste module naming collision: next-on-netlify-test
  The following files share their name; please adjust your hasteImpl:
    * <rootDir>/fixtures/package.json
    * <rootDir>/builds/customNextDistDir.test/package.json

Author: FinnWoelm

package.json

@@ -25,7 +25,7 @@
     "/lib"
   ],
   "scripts": {
-    "test": "jest",
+    "test": "jest --config tests/jest.config.js",
     "cypress:local": "env CYPRESS_DEPLOY=local cypress run --config-file false",
     "cypress:netlify": "env CYPRESS_DEPLOY=netlify cypress run --config-file false"
   },

tests/jest.config.js

@@ -1,4 +1,5 @@
 module.exports = {
-  // Do not scan the ./builds/ folder for tests or package.json files
-  testPathIgnorePatterns: ["./builds/"]
+  // Do not scan the ./builds/ folder and the Cypress folder for tests or
+  // package.json files
+  modulePathIgnorePatterns: ["./builds/", "<rootDir>/cypress/"]
 };