Fix caching test

This PR fixes the caching tests in SpotCacheTest. The default caching mechanism in the WiScout project is the dummy cache, which implements the caching interface but doesn't actually cache. This overrides the CACHES setting for this test only to ensure that a real caching implementation (in this case, Local Memory) is used.

Please review: @NUWAN.KUMARASIRI @TREFILEK @bjsousa