fix: upgrade i18next from 21.6.3 to 21.6.4 (#385)

Snyk has created this PR to upgrade i18next from 21.6.3 to 21.6.4.

See this package in npm:
https://www.npmjs.com/package/i18next

See this project in Snyk:
https://app.snyk.io/org/helsearbeidsgiver/project/8e6cf866-6de1-4306-a9c3-92d168657a92?utm_source=github&utm_medium=referral&page=upgrade-pr

package.json

@@ -42,7 +42,7 @@
     "classnames": "^2.3.1",
     "constate": "^3.3.0",
     "dayjs": "^1.10.7",
-    "i18next": "^21.5.4",
+    "i18next": "^21.6.4",
     "lodash.throttle": "^4.1.1",
     "nav-datovelger": "^12.1.2",
     "nav-frontend-alertstriper": "^4.0.1",