Add a comment documenting the package version being used (#2918)

scripts/release/update-comment.js

@@ -0,0 +1,27 @@
+#!/usr/bin/env node
+
+const fs = require('fs');
+const glob = require('glob');
+const proc = require('child_process');
+
+const gitStatus = proc.execFileSync('git', ['status', '--porcelain', '-uno', 'contracts']);
+
+if (gitStatus.length > 0) {
+  console.error('Contracts directory is not clean');
+  process.exit(1);
+}
+
+const { version } = require('../../package.json');
+
+const files = glob.sync('contracts/!(mocks)/**/*.sol');
+
+for (const file of files) {
+  const current = fs.readFileSync(file, 'utf8');
+  const updated = current.replace(
+    /(\/\/ SPDX-License-Identifier:.*)$(\n\/\/ OpenZeppelin Contracts v.*$)?/m,
+    `$1\n// OpenZeppelin Contracts v${version} (${file.replace('contracts/', '')})`,
+  );
+  fs.writeFileSync(file, updated);
+}
+
+proc.execFileSync('git', ['add', '--update', 'contracts']);