Fix jQuery version

[fbacall]

Summary of changes

• Load jQuery 3.7.1 (from jquery-rails) instead of version 1.x.
• Fix JS eval error when loading calendar.
• Bump jquery-rails version

Motivation and context

Events calendar was not loading due to CSP violation caused by old jQuery trying to use eval.

Checklist

• I have read and followed the CONTRIBUTING guide.
• I confirm that I have the authority necessary to make this contribution on behalf of its copyright owner and agree to license it to the TeSS codebase under the BSD license.

[Copilot]

Pull request overview

This PR updates the Rails asset pipeline to load modern jQuery (via jquery-rails) and adjusts the events calendar AJAX loading to avoid CSP issues caused by executing returned JavaScript via eval.

Changes:

• Bump jquery-rails to 4.6.1 and switch the asset manifest to require jquery3 (jQuery 3.7.1).
• Change calendar loading to use jQuery’s built-in dataType: 'script' execution instead of eval.
• Remove the explicit .js format from the calendar URL so format negotiation can occur via the AJAX request.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
Gemfile.lock	Bumps jquery-rails to 4.6.1.
app/views/events/index.html.erb	Adjusts calendar tab’s data-calendar URL to drop the explicit format: :js.
app/assets/javascripts/application.js	Loads jquery3 and updates calendar AJAX loading to avoid eval.

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[mikesndrs]

probably should add test to check if calendar is available