move blueprints in dedicated folder

app/blueprints/workshops/routes.py

@@ -0,0 +1,15 @@
+from flask import redirect, render_template, url_for
+from . import bp
+
+
+@bp.route('')
+def workshops():
+    return redirect(url_for('main.dashboard'))
+
+
+@bp.route('/fgho_sommerschule_2023')
+def fgho_sommerschule_2023():
+    return render_template(
+        'workshops/fgho_sommerschule_2023.html.j2',
+        title='FGHO Sommerschule 2023',
+    )