chore(deps): bump squidfunk/mkdocs-material in /docs

Bumps squidfunk/mkdocs-material from `96abcbb` to `257eca8`.

---
updated-dependencies:
- dependency-name: squidfunk/mkdocs-material
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

docs/Dockerfile

@@ -1,5 +1,5 @@
 # v9.1.18
-FROM squidfunk/mkdocs-material@sha256:96abcbb1bb6d4d79a6a142fe88150b3862b2b297fe45e6656b154d978b1787eb
+FROM squidfunk/mkdocs-material@sha256:257eca88da7f42242cd05e8cebf6d10ebd079edc207b089ad3f4f1ad107b0348
 # pip-compile --generate-hashes --output-file=requirements.txt requirements.in
 COPY requirements.txt /tmp/
 RUN pip install --require-hashes -r /tmp/requirements.txt