Disable ubuntu-22.04 arm64 build for now

Author: kateinoigakukun

.github/workflows/ci-image.yml

@@ -24,7 +24,7 @@ jobs:
             tags:
               - ghcr.io/swiftwasm/swift-ci:main-ubuntu-20.04
           - dockerfile: swift-ci/main/ubuntu/22.04/Dockerfile
-            platforms: linux/amd64,linux/arm64
+            platforms: linux/amd64 # FIXME: linux/arm64 build didn't work on QEMU
             tags:
               - ghcr.io/swiftwasm/swift-ci:main-ubuntu-22.04
           - dockerfile: swift-ci/main/amazon-linux/2/Dockerfile