cmd/kg/main.go: replace deprecated prom collectors (#255)

Signed-off-by: leonnicolas <leonloechner@gmx.de>

vendor/github.com/json-iterator/go/iter_float.go

@@ -288,6 +288,9 @@ non_decimal_loop:
 				return iter.readFloat64SlowPath()
 			}
 			value = (value << 3) + (value << 1) + uint64(ind)
+			if value > maxFloat64 {
+				return iter.readFloat64SlowPath()
+			}
 		}
 	}
 	return iter.readFloat64SlowPath()