ci: Add Alpine

ci: Add Alpine

Add setup action for Alpine and start building it. Unfortunately the
testsuite is not ready yet and fails to build like this:

	../testsuite/path.c:219:14: error: conflicting types for '__xstat64';
	have 'int(int,  const char *, struct stat64 *)'
	  219 | WRAP_VERSTAT(__x,64);
	      |              ^~~

Add everything needed on the setup action, so when the underlying issue
is fixed, the testsuite can be enabled in CI.

Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>
Reviewed-by: Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Link: https://github.com/kmod-project/kmod/pull/44