Add average round duration

[nicoSWD]

Changes:

• Provide better end times by using average round duration from past events
• Add tests

[github-actions]

This PR produces the following changes in the calendar

✏️ Changed Events:

🏆 IFSC: World Cup - Keqiao

Changed Rounds

Round	Key	Old Value	New Value
Women's Boulder Qualification
👉	ends_at	2024-04-08T11:00:00+08:00	2024-04-08T10:30:00+08:00
Men's Boulder Qualification
👉	ends_at	2024-04-08T18:00:00+08:00	2024-04-08T17:30:00+08:00

---

🏆 IFSC: World Cup - Wujiang

Changed Rounds

Round	Key	Old Value	New Value
Men's & Women's Lead Semi-Final
👉	ends_at	2024-04-13T16:30:00+08:00	2024-04-13T17:30:00+08:00
Women's Lead Final
👉	ends_at	2024-04-14T20:30:00+08:00	2024-04-14T21:00:00+08:00
Men's Lead Final
👉	ends_at	2024-04-14T20:30:00+08:00	2024-04-14T20:00:00+08:00

---

🏆 IFSC: World Cup - Salt Lake City

Changed Rounds

Round	Key	Old Value	New Value
Women's Speed Final
👉	ends_at	2024-05-04T22:00:00-07:00	2024-05-04T21:00:00-07:00
Men's Speed Final
👉	ends_at	2024-05-05T22:00:00-07:00	2024-05-05T21:30:00-07:00

---

🏆 IFSC: World Cup - Chamonix

Changed Rounds

Round	Key	Old Value	New Value
Men's & Women's Speed Qualification
👉	ends_at	2024-07-12T20:45:00+02:00	2024-07-12T20:15:00+02:00
Men's & Women's Speed Final
👉	ends_at	2024-07-13T23:00:00+02:00	2024-07-13T22:30:00+02:00
Men's Lead Final
👉	ends_at	2024-07-14T23:25:00+02:00	2024-07-14T22:25:00+02:00

---

🏆 IFSC: World Cup - Briancon

Changed Rounds

Round	Key	Old Value	New Value
Men's & Women's Speed Qualification
👉	ends_at	2024-07-17T14:00:00+02:00	2024-07-17T13:30:00+02:00
Men's & Women's Speed Final
👉	ends_at	2024-07-17T22:00:00+02:00	2024-07-17T21:30:00+02:00

---

🏆 IFSC: World Cup - Koper

Changed Rounds

Round	Key	Old Value	New Value
Men's Lead Final
👉	ends_at	2024-09-07T22:00:00+02:00	2024-09-07T21:00:00+02:00

---

🏆 IFSC: World Cup - Prague

Changed Rounds

Round	Key	Old Value	New Value
Men's Boulder Qualification
👉	ends_at	2024-09-20T11:00:00+02:00	2024-09-20T10:30:00+02:00
Women's Boulder Qualification
👉	ends_at	2024-09-20T18:00:00+02:00	2024-09-20T17:30:00+02:00

---