Add Semrush in taxonomy (#1647)

Author: AlteredCoder

taxonomy/false_positives.json

@@ -79,6 +79,11 @@
         "label": "Googlebot SEO crawler",
         "name": "seo:googlebot"
     },
+    "seo:semrush": {
+        "description": "IP belongs to Semrush SEO crawler and should not be flagged as a threat.",
+        "label": "Semrush SEO crawler",
+        "name": "seo:semrush"
+    },
     "seo:bingbot": {
         "description": "IP belongs to Bingbot SEO crawler and should not be flagged as a threat.",
         "label": "Bingbot SEO crawler",