Fix JCalendar LGPL detected as GPL

[Kaushik-Kumar-CEG]

Fixes #4513

JCalendar's LGPL header was getting flagged as GPL because the text is very similar to an existing GPL rule (gpl-2.0-plus_60.RULE).

Here is what this PR does to fix it:

1. Added required phrases to the old GPL rule so it ignores the JCalendar text
2. Added a new rule (lgpl-2.0-plus_jcalendar_1.RULE) to properly catch this specific LGPL variant
3. Added data driven regression tests to make sure it stays fixed

Before :

After:

Tasks

• Reviewed contribution guidelines
• PR is descriptively titled 📑 and links the original issue above 🔗
• Tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR
  Run tests locally to check for errors.
• Commits are in uniquely-named feature branch and has no merge conflicts 📁
• Updated documentation pages (if applicable)
• Updated CHANGELOG.rst (if applicable)