Update CI to run on Ubuntu 22.04 (#1632)

This allows us compile binaryen from source during CI, which was broken
recently.
See https://github.com/WebAssembly/binaryen/issues/8067 and
https://github.com/WebAssembly/binaryen/pull/8071

.circleci/config.yml

diff --git a/.circleci/config.yml b/.circleci/config.yml
index 09eeb13..b8e637d 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -6,7 +6,7 @@
 executors:
   ubuntu:
     docker:
-      - image: buildpack-deps:focal
+      - image: buildpack-deps:jammy
   mac_arm64:
     environment:
       EMSDK_NOTTY: "1"