Run CI on 32 bit operating system

Some of our code may break in 32 bit operating systems (386, some arm flavors). We already saw #2415 and there are likely other issues hard to detect with the human eye, even in the `pkg/scale` package. Running our CI (at least once) with 32 bit (maybe emulated on 64bit so it's faster) would help detect issues before we cross compile Gossamer.

:warning: blocked by #2585 since wasmer (probably) doesn't support 32 bit OSes well I believe.
This is important for cross compilation, so especially once wasmer is dropped (it makes cross compilation nearly impossible)