chore: update changelog for 3.1.0

[coriolinus]

What's new in this PR

---

PR Submission Checklist for internal contributors

• The PR Title
  • conforms to the style of semantic commits messages¹ supported in Wire's Github Workflow²
  • contains a reference JIRA issue number like SQPIT-764
  • answers the question: If merged, this PR will: ... ³

1. https://sparkbox.com/foundry/semantic_commit_messages
2. https://github.com/wireapp/.github#usage
3. E.g. feat(conversation-list): Sort conversations by most emojis in the title #SQPIT-764.

[github-actions]

Bencher Report

Branch	prgn/chore/update-changelog-v3.1.0
Testbed	ubuntu-latest

Click to view all benchmark results

Benchmark	Latency	milliseconds (ms)
Commit add f(group size)/cs1/mem/1002	📈 view plot 🚷 view threshold	19.14
Commit add f(group size)/cs1/mem/2	📈 view plot 🚷 view threshold	6.92
Commit add f(group size)/cs1/mem/202	📈 view plot 🚷 view threshold	9.49
Commit add f(group size)/cs1/mem/402	📈 view plot 🚷 view threshold	11.99
Commit add f(group size)/cs1/mem/602	📈 view plot 🚷 view threshold	15.23
Commit add f(group size)/cs1/mem/802	📈 view plot 🚷 view threshold	17.19
Commit add f(number clients)/cs1/mem/1002	📈 view plot 🚷 view threshold	983.87
Commit add f(number clients)/cs1/mem/2	📈 view plot 🚷 view threshold	6.96
Commit add f(number clients)/cs1/mem/202	📈 view plot 🚷 view threshold	84.53
Commit add f(number clients)/cs1/mem/402	📈 view plot 🚷 view threshold	219.56
Commit add f(number clients)/cs1/mem/602	📈 view plot 🚷 view threshold	425.87
Commit add f(number clients)/cs1/mem/802	📈 view plot 🚷 view threshold	671.32
Commit pending proposals f(group size)/cs1/mem/1002	📈 view plot 🚷 view threshold	116.21
Commit pending proposals f(group size)/cs1/mem/2	📈 view plot 🚷 view threshold	28.42
Commit pending proposals f(group size)/cs1/mem/202	📈 view plot 🚷 view threshold	45.95
Commit pending proposals f(group size)/cs1/mem/402	📈 view plot 🚷 view threshold	60.99
Commit pending proposals f(group size)/cs1/mem/602	📈 view plot 🚷 view threshold	79.30
Commit pending proposals f(group size)/cs1/mem/802	📈 view plot 🚷 view threshold	94.88
Commit pending proposals f(pending size)/cs1/mem/1	📈 view plot 🚷 view threshold	19.21
Commit pending proposals f(pending size)/cs1/mem/101	📈 view plot 🚷 view threshold	115.46
Commit pending proposals f(pending size)/cs1/mem/21	📈 view plot 🚷 view threshold	36.07
Commit pending proposals f(pending size)/cs1/mem/41	📈 view plot 🚷 view threshold	56.79
Commit pending proposals f(pending size)/cs1/mem/61	📈 view plot 🚷 view threshold	75.59
Commit pending proposals f(pending size)/cs1/mem/81	📈 view plot 🚷 view threshold	95.52
Commit remove f(group size)/cs1/mem/1002	📈 view plot 🚷 view threshold	28.12
Commit remove f(group size)/cs1/mem/2	📈 view plot 🚷 view threshold	6.80
Commit remove f(group size)/cs1/mem/202	📈 view plot 🚷 view threshold	9.15
Commit remove f(group size)/cs1/mem/402	📈 view plot 🚷 view threshold	11.98
Commit remove f(group size)/cs1/mem/602	📈 view plot 🚷 view threshold	17.30
Commit remove f(group size)/cs1/mem/802	📈 view plot 🚷 view threshold	22.28
Commit remove f(number clients)/cs1/mem/1002	📈 view plot 🚷 view threshold	30.58
Commit remove f(number clients)/cs1/mem/2	📈 view plot 🚷 view threshold	137.67
Commit remove f(number clients)/cs1/mem/202	📈 view plot 🚷 view threshold	115.83
Commit remove f(number clients)/cs1/mem/402	📈 view plot 🚷 view threshold	93.99
Commit remove f(number clients)/cs1/mem/602	📈 view plot 🚷 view threshold	72.52
Commit remove f(number clients)/cs1/mem/802	📈 view plot 🚷 view threshold	51.03
Commit update f(group size)/cs1/mem/1002	📈 view plot 🚷 view threshold	138.14
Commit update f(group size)/cs1/mem/2	📈 view plot 🚷 view threshold	7.09
Commit update f(group size)/cs1/mem/202	📈 view plot 🚷 view threshold	33.64
Commit update f(group size)/cs1/mem/402	📈 view plot 🚷 view threshold	60.28
Commit update f(group size)/cs1/mem/602	📈 view plot 🚷 view threshold	86.47
Commit update f(group size)/cs1/mem/802	📈 view plot 🚷 view threshold	111.88

🐰 View full continuous benchmarking report in Bencher