just do it

.devcontainer/devcontainer.json

@@ -8,7 +8,7 @@
 			// Update the VARIANT arg to pick a version of Go: 1, 1.18, 1.17
 			// Append -bullseye or -buster to pin to an OS version.
 			// Use -bullseye variants on local arm64/Apple Silicon.
-			"VARIANT": "1.18-bullseye",
+			"VARIANT": "1.21-bullseye",
 			// Options
 			"NODE_VERSION": "none"
 		}