fix: run release script asynchronously

lib/promote_release.js

@@ -5,7 +5,7 @@ const { promises: fs } = require('fs');
 const semver = require('semver');
 
 const { getMergedConfig } = require('./config');
-const { runSync } = require('./run');
+const { runSync, runAsync } = require('./run');
 const auth = require('./auth');
 const PRData = require('./pr_data');
 const PRChecker = require('./pr_checker');
@@ -101,7 +101,7 @@ class ReleasePromotion {
 
     // Merge vX.Y.Z-proposal into vX.x.
     cli.startSpinner('Merging proposal branch');
-    await this.mergeProposalBranch();
+    this.mergeProposalBranch();
     cli.stopSpinner('Merged proposal branch');
 
     // Cherry pick release commit to master.
@@ -151,7 +151,7 @@ class ReleasePromotion {
     const keyPath = await cli.prompt(
       `Please enter the path to your ssh key (Default ${defaultKeyPath}): `,
       { questionType: 'input', defaultAnswer: defaultKeyPath });
-    this.promoteAndSignRelease(keyPath);
+    await this.promoteAndSignRelease(keyPath);
 
     cli.separator();
     cli.ok(`Release promotion for ${version} complete.\n`);
@@ -292,7 +292,7 @@ class ReleasePromotion {
     ]);
   }
 
-  async mergeProposalBranch() {
+  mergeProposalBranch() {
     const { stagingBranch, versionComponents, version } = this;
 
     const releaseBranch = `v${versionComponents.major}.x`;
@@ -313,8 +313,8 @@ class ReleasePromotion {
     return runSync('git', ['push', 'upstream', tagVersion]);
   }
 
-  promoteAndSignRelease(keyPath) {
-    return runSync('./tools/release.sh', ['-i', keyPath]);
+  async promoteAndSignRelease(keyPath) {
+    await runAsync('./tools/release.sh', ['-i', keyPath]);
   }
 
   cherryPickToMaster() {