GHA: windows updates for zip

Now that we install Rtools40, we can use zip again
from the Makefile.

[ci skip]

tools/build/windows/Makefile

@@ -20,7 +20,7 @@ lib/R-%.done: lib/%/_pak.done
 	rm -rf lib/$*/pak/library/_cache
 	rm -rf lib/$*/pak/library/*/help
 	rm -rf lib/$*/pak/library/*/doc
-	cd lib/$* && Compress-Archive -path pak -destination pak_$(PAKVERSION).zip
+	cd lib/$* && zip -r pak_$(PAKVERSION).zip pak
 	touch $@
 
 lib/%/pak: