Describe the bug
I am trying to add regex to capture secrets from jmeter files. the regex is working in online golang tool. but when i try i with gitleaks it is not working

To Reproduce

1. use below custom rule
   [[rules]]
   description = "JMX API Key"
   id = "jmx-api-key"
   regex = '''^\s*<elementProp name="(?:client_secret)"[^>]+>\n(.* name="Argument.name".\n). name="Argument.value">([a-zA-Z0-9]{8,})<[/][^>]+>\n'''
   [rules.allowlist]
   paths = [
   '''(?i)\b\wlnp\w.jmx''',
   ]

2. Test data used:
   <elementProp name="client_secret" elementType="Argument"> <stringProp name="Argument.name">client_id</stringProp> <stringProp name="Argument.va1ddlue">${client_id}</stringProp> <stringProp name="Argument.metadata">=</stringProp> </elementProp> <elementProp name="client_secret" elementType="Argument"> <stringProp name="Argument.name">client_secret</stringProp> <stringProp name="Argument.value">UiI6S2TNzIelSDXA</stringProp> <stringProp name="Argument.metadata">=</stringProp> </elementProp> <elementProp name="scope_op6" elementType="Argument"> <stringProp name="Argument.name">scope_op6</stringProp> <stringProp name="Argument.value">PARTNER_PAYMENT_HAS_PAYMENT_METHOD_OIC</stringProp> <stringProp name="Argument.desc">USER_PAYMENT_METHODS_MANAGE</stringProp> <stringProp name="Argument.metadata">=</stringProp> </elementProp>

Expected behavior
This should match hardcoded client_secret in jmx file

Screenshots
working screenshot from online tool.
https://www.akto.io/tools/go-regex-tester

Basic Info (please complete the following information):

• OS: windows
• Gitleaks Version: 8.18.4

Additional context
N/A