add --gpgSign/-S option

lib/promote_release.js

@@ -17,6 +17,9 @@ export default class ReleasePromotion extends Session {
     this.isLTS = false;
     this.ltsCodename = '';
     this.date = '';
+    this.gpgSign = argv?.['gpg-sign']
+      ? (argv['gpg-sign'] === true ? ['-S'] : ['-S', argv['gpg-sign']])
+      : [];
   }
 
   async promote() {
@@ -375,6 +378,7 @@ export default class ReleasePromotion extends Session {
     await forceRunAsync('git', ['add', filePath], { ignoreFailure: false });
     return forceRunAsync('git', [
       'commit',
+      ...this.gpgSign,
       '-m',
       `Working on ${workingOnVersion}`,
       '-m',
@@ -427,6 +431,7 @@ export default class ReleasePromotion extends Session {
     await this.tryResetBranch();
 
     // There will be conflicts, we do not want to treat this as a failure.
-    await forceRunAsync('git', ['cherry-pick', releaseCommitSha], { ignoreFailure: true });
+    await forceRunAsync('git', ['cherry-pick', ...this.gpgSign, releaseCommitSha],
+      { ignoreFailure: true });
   }
 }