Auto update CDN URLs in README.md in release PR (#5545)

* Add script to bump major version in README

On lines 29-32, we could alternatively use `replaceAll`, I opted not to
as it is not yet(?) part of an LTS release of NodeJS.

* Bump CDN version in README automatically for new releases

* Rename "bump-cdn-version.js" to "update-cdn-urls.js"

* Update names of file-level constants in update-cdn-urls.js

* Rename workflow setp for updating CDN URLs

* Rename packageJsonFile constant in update-cdn-urls

* Remove semver dependency

* Generalize update-cdn-urls script

.github/workflows/create-release.yml

@@ -27,6 +27,8 @@ jobs:
           ref: develop
       - name: Bump version
         run: node ./scripts/bump-version.js "${{ needs.release-pr.outputs.new-version }}"
+      - name: Update major version in CDN URLs
+        run: node ./scripts/update-cdn-urls.js
       - name: Update slugs table
         run: node ./scripts/build-slugs-table.js
       - name: Commit version bump

scripts/update-cdn-urls.js

@@ -0,0 +1,47 @@
+#!/usr/bin/env node
+/**
+ * @fileoverview
+ * Updates the CDN URLs in the README.md to match the major version in the
+ * NPM package manifest. Does nothing if the README.md is already up-to-date.
+ */
+
+const fs = require("fs");
+const path = require("path");
+
+const rootDir = path.resolve(__dirname, "..");
+const packageJsonFile = path.resolve(rootDir, "package.json");
+const readmeFile = path.resolve(rootDir, "README.md");
+
+function getMajorVersion(semVerVersion) {
+  const majorVersionAsString = semVerVersion.split('.')[0];
+  return parseInt(majorVersionAsString);
+}
+
+function getManifest() {
+  const manifestRaw = fs.readFileSync(packageJsonFile).toString();
+  return JSON.parse(manifestRaw);
+}
+
+function updateVersionInReadmeIfNecessary(majorVersion) {
+  let content = fs.readFileSync(readmeFile).toString();
+
+  content = content.replace(
+    /simple-icons@v[0-9]+/g,
+    `simple-icons@v${majorVersion}`,
+  );
+
+  fs.writeFileSync(readmeFile, content);
+}
+
+function main() {
+  try {
+    const manifest = getManifest();
+    const majorVersion = getMajorVersion(manifest.version);
+    updateVersionInReadmeIfNecessary(majorVersion);
+  } catch (error) {
+    console.error("Failed to update CDN version number:", error);
+    process.exit(1);
+  }
+}
+
+main();