[m3u-expiration-notifier]: Add M3U Expiration Notifier plugin

[barryanderson]

About this submission

New plugin submission (external). Checks M3UAccountProfile.exp_date on a configurable schedule and emails the user before (and when) M3U account profiles expire. Source: https://github.com/barryanderson/dispatcharr-m3u-expiration-notifier

Pre-submission checklist

If this is a new plugin:

• Plugin folder is named lowercase-kebab-case
• plugin.json contains all required fields (name, version, description, author or maintainers, license)
• My GitHub username is in author or maintainers
• license is a valid OSI-approved SPDX identifier (e.g. MIT, Apache-2.0)
• I have tested the plugin against a running Dispatcharr instance

[dispatcharr-plugins-bot]

Plugin Validation Results

Modified plugins: 1

Plugin: m3u-expiration-notifier

Checks your M3U account expiration dates on a schedule and emails you before (and when) they expire.

Source Repository

Check	Status	Details
Required fields	✅	All required fields present
Release artifact	✅	Artifact reachable at resolved URL
Maintainers	✅	barryanderson
License	✅	MIT - MIT License
Permission	✅	New plugin - barryanderson listed in author/maintainers
Version	✅	1.0.0
Version bump	✅	New plugin

View release v1.0.0 on GitHub

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🎉 All validation checks passed!

This PR modifies 1 plugin(s) and all checks have passed.