Upgrade MicroPython to 2.2.1 and 1.1.1. (#1072)

* Use staging simulator on non-production deploys. Staging is using 2.2.1-based simulator.
* Update typeshed for frozenset - microbit-foundation/micropython-microbit-stubs#85
* Add issue template for future upgrades.

Upstream releases:
https://github.com/bbcmicrobit/micropython/releases/tag/v1.1.1
https://github.com/microbit-foundation/micropython-microbit-v2/releases/tag/v2.1.1

We'll run with this on beta for a day or two then push live.

Closes #1071
Closes #1001

Author: microbit-matt-hillsdon

.github/ISSUE_TEMPLATE/micropython-update.md

@@ -0,0 +1,33 @@
+---
+name: Upgrade MicroPython
+about: Template for MicroPython upgrades
+---
+
+## New MicroPython releases
+
+**Link new releases here**
+
+## Todo
+
+Simulator:
+
+- [ ] Review changelogs and diff to determine simulator changes, stubs changes any other documentation changes
+- [ ] Raise educational content impact to Foundation education team (likely already in hand or low priority)
+- [ ] Update simulator as required
+- [ ] Run through simulator examples in simulator demo.html
+- [ ] Test simulator in Python Editor (locally)
+- [ ] Merge simulator changes
+
+Editor:
+
+- [ ] Update stubs as required
+- [ ] Update MicroPython hex files and version metadata in the editor
+- [ ] PR with updated sim (via staging) and stubs
+- [ ] Release stubs
+- [ ] Test and merge PR
+
+Now or later:
+
+- [ ] Release simulator
+- [ ] Update and publish simulator versioning CloudFront function
+- [ ] Release editor