chore(stacks): remove pushgateway

Author: duanhongyi

scripts/checker.py

@@ -271,12 +271,6 @@
         "owner": "prometheus",
         "match": "^v[0-9]{1,}\.[0-9]{1,}\.[0-9]{1,}$",
     },
-    "pushgateway": {
-        "name": "pushgateway",
-        "type": "github",
-        "owner": "prometheus",
-        "match": "^v[0-9]{1,}\.[0-9]{1,}\.[0-9]{1,}$",
-    },
     "node_exporter": {
         "name": "node_exporter",
         "type": "github",