build(deps): bump matplotlib from 3.8.3 to 3.8.4

Bumps [matplotlib](https://github.com/matplotlib/matplotlib) from 3.8.3 to 3.8.4.
- [Release notes](https://github.com/matplotlib/matplotlib/releases)
- [Commits](matplotlib/matplotlib@v3.8.3...v3.8.4)

---
updated-dependencies:
- dependency-name: matplotlib
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -1,4 +1,4 @@
 astropy==6.0.1
-matplotlib==3.8.3
+matplotlib==3.8.4
 numpy==1.26.4
 scipy==1.13.0