fix: package.json & yarn.lock to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-BABELTRAVERSE-5962462
- https://snyk.io/vuln/SNYK-JS-ELLIPTIC-7577916
- https://snyk.io/vuln/SNYK-JS-ELLIPTIC-7577917
- https://snyk.io/vuln/SNYK-JS-ELLIPTIC-7577918
- https://snyk.io/vuln/SNYK-JS-ANSIREGEX-1583908
- https://snyk.io/vuln/SNYK-JS-BRACES-6838727
- https://snyk.io/vuln/SNYK-JS-FASTXMLPARSER-3325616
- https://snyk.io/vuln/SNYK-JS-JSON5-3182856
- https://snyk.io/vuln/SNYK-JS-SHELLQUOTE-1766506
- https://snyk.io/vuln/SNYK-JS-BROWSERIFYSIGN-6037026
- https://snyk.io/vuln/SNYK-JS-FASTXMLPARSER-5668858
- https://snyk.io/vuln/SNYK-JS-FASTXMLPARSER-7573289
- https://snyk.io/vuln/SNYK-JS-NODEFETCH-2342118

package.json

@@ -30,15 +30,15 @@
     "@headlessui/react": "1.5.0",
     "@heroicons/react": "1.0.6",
     "@kawalcovid19/tailwind-preset-wbw": "^0.1.1",
-    "@netlify/plugin-nextjs": "3.9.2",
+    "@netlify/plugin-nextjs": "5.0.0",
     "@tailwindcss/forms": "^0.4.0",
     "@tailwindcss/typography": "0.4.1",
     "clsx": "^1.1.1",
     "cross-fetch": "^3.1.5",
     "globby": "^11.1.0",
     "htmr": "^1.0.1",
     "itemsjs": "^2.1.13",
-    "next": "11.1.4",
+    "next": "12.0.8",
     "next-pwa": "^5.4.7",
     "next-seo": "^4.29.0",
     "nprogress": "^0.2.0",