Fine tune blob uploads

src/cache.ts

@@ -465,6 +465,8 @@ async function saveCacheV2(
   // Override UploadOptions to force the use of Azure
   options = {
     ...options,
+    uploadChunkSize: 64 * 1024 * 1024, // 128MiB
+    uploadConcurrency: 8, // 8 workers for parallel upload
     useAzureSdk: true
   }
   const compressionMethod = await utils.getCompressionMethod()