gha: disable cross-compile for linux

GHA currently only has x86 machines, and the "cross" target in moby
does not include containerd and runc.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: thaJeztah

.github/workflows/ci.yml

@@ -37,9 +37,11 @@ jobs:
       matrix:
         platform:
           - linux/amd64
-          - linux/arm/v6
-          - linux/arm/v7
-          - linux/arm64
+          # TODO(thaJeztah) re-enable once moby cross-compile also builds containerd
+          # and runc, or once we build containerd and runc using containerd-packaging
+          # - linux/arm/v6
+          # - linux/arm/v7
+          # - linux/arm64
           - darwin/amd64
           - darwin/arm64
           - windows/amd64