Check cached sources with upstream after the cache TTL (closes #69) (#350)

internal/providers/providers.go

@@ -83,6 +83,7 @@ func newCache(lc fx.Lifecycle, params cacheParams) (*imgcache.Cache, error) {
 	cache, err := imgcache.NewCache(db, imgcache.Config{
 		StateDir:    cfg.StateDir,
 		NegativeTTL: imgcache.DefaultNegativeTTL,
+		CacheTTL:    imgcache.DefaultCacheTTL,
 		MaxBytes:    maxBytes,
 		Logger:      params.Logger.Get(),
 	}, params.MetricsRegistry)