Update build-bundles to use circuitpython 2.1.0.

Author: dhalbert

build-bundles.py

@@ -173,5 +173,5 @@ def add_file(bundle, src_file, zip_name):
         print("Go ahead and tag. I'll wait.")
         sys.exit(3)
     build_bundle("1.0.0")
-    build_bundle("2.0.0")
+    build_bundle("2.1.0")