Remove deprecated course module

[JonasWanke]

Please merge #148 first!

[unicorn-bot]

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[jwbot]

	8 Warnings
⚠️	lib/app/services/navigation.dart#L42 - Avoid print calls in production code
⚠️	lib/app/widgets/hpi_app.dart#L130 - The value of the field ‘news’ isn’t used
⚠️	lib/crashreporting/utils.dart#L45 - Avoid print calls in production code
⚠️	lib/crashreporting/utils.dart#L47 - Avoid print calls in production code
⚠️	lib/feedback/widgets/feedback_dialog.dart#L160 - Avoid print calls in production code
⚠️	lib/main.dart#L25 - Avoid slow async dart:io methods
⚠️	lib/news/widgets/article_page.dart#L140 - Avoid print calls in production code
⚠️	lib/news/widgets/article_preview.dart#L43 - Avoid print calls in production code

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