[cli][client][tests] update to node14-compatible target (drop support for node12) (#7865)

Node 12 is EOL and we're starting to reference packages that don't install on node lower than 14, such as nuxt@3 and remix. Let's update to 14 for now.

---

Reimplements: https://github.com/vercel/vercel/pull/7819

test/lib/deployment/fetch-retry.js

@@ -1,11 +1,17 @@
 const fetch = require('node-fetch');
 const retryBailByDefault = require('./retry-bail-by-default.js');
 
-async function fetchRetry(...args) {
+const ABSOLUTE_URL_PATTERN = /^https?:\/\//i;
+
+async function fetchRetry(url, ...rest) {
+  if (!ABSOLUTE_URL_PATTERN.test(url)) {
+    throw new Error(`fetch url must be absolute: "${url}"`);
+  }
+
   return await retryBailByDefault(
     async canRetry => {
       try {
-        return await fetch(...args);
+        return await fetch(url, ...rest);
       } catch (error) {
         if (error.type === 'request-timeout') {
           // FetchError: network timeout at: ...