build: strip v in the getElectronVersion helper

BUILD.gn

@@ -113,6 +113,7 @@ electron_version = exec_script("script/print-version.py",
                                [
                                  ".git/packed-refs",
                                  ".git/HEAD",
+                                 "script/lib/get-version.js",
                                ])
 
 if (is_mas_build) {

script/lib/get-version.js

@@ -18,5 +18,5 @@ module.exports.getElectronVersion = () => {
     console.error(output.stderr);
     throw new Error('Failed to get current electron version');
   }
-  return output.stdout.toString().trim();
+  return output.stdout.toString().trim().replace(/^v/g, '');
 };