fix fuzzing self-contained input requirement

[dogancanbakir]

Proposed changes

Closes #4509

$ cat test.yaml
id: fuzzing-temp
info:
  name: Fuzzing Template
  author: custom
  severity: low

self-contained: true

http:
  - method: GET
    path:
      - "https://example.com/?param_name=123"
      
    payloads:
      payload_set1:
        - "1"
        - "2"
    attack: clusterbomb
    fuzzing:
      - part: query
        type: replace
        mode: single
        keys:
          - "param_name"
        fuzz:
          - "{{payload_set1}}"
    matchers:
      - type: status
        status:
          - 200

$ go run . -t ./test.yaml

                     __     _
   ____  __  _______/ /__  (_)
  / __ \/ / / / ___/ / _ \/ /
 / / / / /_/ / /__/ /  __/ /
/_/ /_/\__,_/\___/_/\___/_/   v3.1.4-dev

                projectdiscovery.io

[INF] Current nuclei version: v3.1.4-dev (development)
[INF] Current nuclei-templates version: v9.7.2 (latest)
[WRN] Scan results upload to cloud is disabled.
[INF] New templates added in latest release: 61
[INF] Templates loaded for current scan: 1
[WRN] Executing 1 unsigned templates. Use with caution.
[fuzzing-temp] [http] [low] https://example.com/?param_name=1
[fuzzing-temp] [http] [low] https://example.com/?param_name=2

Checklist

• Pull request is created against the dev branch
• All checks passed (lint, unit/integration/regression tests etc.) with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)