Support whole number float64 type for severity parsing

[jsirianni]

Severity parsing should support float64 values when they are whole numbers. Golang JSON parsing will consider any number a float64 unless it is unmarshalled to a struct using specific types (int, int64, float64, etc).

Trying to parse the pri field as a Severity will result in an "unsupported type float64" error.

{
  "uid": 62,
  "time": 1617410898,
  "pri": 6,
  "tag": "pve-ha-lrm",
  "pid": 33690,
  "node": "pve-1",
  "user": "root@pam",
  "msg": "end task UPID:pve-1:0000839B:000C5C3F:6067BB15:qmshutdown:100:root@pam: OK"
}

Additional context:

• Stanza PR support float64 values as long as they are whole numbers observIQ/stanza#268
• Stanza Issue Support float64 for severity parsing observIQ/stanza#267

[djaglowski]

LGTM