chore(deps): bump squidfunk/mkdocs-material from cbfecae to a4cfa88 in /docs (aws-powertools#3175)

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

Bumps squidfunk/mkdocs-material from `cbfecae` to `a4cfa88`.

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

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

Author: dependabot[bot]

docs/Dockerfile

@@ -1,5 +1,5 @@
 # v9.1.18
-FROM squidfunk/mkdocs-material@sha256:cbfecae461533759a5b376ef7ee3ee65cf328536261d28ae35df944c96e06867
+FROM squidfunk/mkdocs-material@sha256:a4cfa88f5db3f6cdc9d97966d60a1003b19c351c603e966500cf30053193ea97
 # pip-compile --generate-hashes --output-file=requirements.txt requirements.in
 COPY requirements.txt /tmp/
 RUN pip install --require-hashes -r /tmp/requirements.txt