ci/arch: add armv7 check

[sreimers]

No description provided.

[alfredh]

I think this one should be good to merge.

I guess we are waiting for the gcc fix:

/home/runner/work/re/re/src/thread/posix.c: In function 'handler':
  /home/runner/work/re/re/src/thread/posix.c:23:16: error: cast from function call of type 'int' to non-matching type 'void *' [-Werror=bad-function-cast]
     23 |         return (void *)(intptr_t)th.func(th.arg);
        |                ^
  cc1: all warnings being treated as errors

Alfred