Ignore values from uba-api when they are zero.

src/Provider/UmweltbundesamtDe/SourceFetcher/Parser/Parser.php

@@ -29,6 +29,10 @@ public function parse(array $response, int $pollutant): array
         foreach ($response['data'] as $stationId => $dataSet) {
             $data = array_pop($dataSet);
 
+            if ($data[2] <= 0) {
+                continue;
+            }
+
             if (!array_key_exists($stationId, $this->stationList)) {
                 continue;
             }