Bump multidict from 6.6.3 to 6.6.4 (#1555)

Bumps [multidict](https://github.com/aio-libs/multidict) from 6.6.3 to 6.6.4.
- [Release notes](https://github.com/aio-libs/multidict/releases)
- [Changelog](https://github.com/aio-libs/multidict/blob/master/CHANGES.rst)
- [Commits](aio-libs/multidict@v6.6.3...v6.6.4)

---
updated-dependencies:
- dependency-name: multidict
  dependency-version: 6.6.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

requirements/test.txt

@@ -2,7 +2,7 @@
 covdefaults
 hypothesis>=6.0
 idna==3.10
-multidict==6.6.3
+multidict==6.6.4
 propcache==0.3.2
 pytest==8.4.2
 pytest-cov>=2.3.1