Update dependency matplotlib to v3.9.0 (#95)

[![Mend
Renovate](https://app.renovatebot.com/images/banner.svg)](https://renovatebot.com)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [matplotlib](https://matplotlib.org)
([source](https://togithub.com/matplotlib/matplotlib)) | `==3.8.4` ->
`==3.9.0` |
[![age](https://developer.mend.io/api/mc/badges/age/pypi/matplotlib/3.9.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![adoption](https://developer.mend.io/api/mc/badges/adoption/pypi/matplotlib/3.9.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![passing](https://developer.mend.io/api/mc/badges/compatibility/pypi/matplotlib/3.8.4/3.9.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/pypi/matplotlib/3.8.4/3.9.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

---

### Release Notes

<details>
<summary>matplotlib/matplotlib (matplotlib)</summary>

###
[`v3.9.0`](https://togithub.com/matplotlib/matplotlib/compare/v3.8.4...v3.9.0)

[Compare
Source](https://togithub.com/matplotlib/matplotlib/compare/v3.8.4...v3.9.0)

</details>

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined),
Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you
are satisfied.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the
rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update
again.

---

- [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check
this box

---

This PR has been generated by [Mend
Renovate](https://www.mend.io/free-developer-tools/renovate/). View
repository job log
[here](https://developer.mend.io/github/Kislovskiy/talks).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzNy4zNjMuNSIsInVwZGF0ZWRJblZlciI6IjM3LjM2My41IiwidGFyZ2V0QnJhbmNoIjoibWFpbiIsImxhYmVscyI6W119-->

2023_PyData_Berlin/requirements.txt

@@ -1,6 +1,6 @@
 numpy==1.26.4
 pandas==2.2.2
-matplotlib==3.8.4
+matplotlib==3.9.0
 pytest==8.2.0
 flake8==7.0.0
 black==24.4.2