chore: bump squidfunk/mkdocs-material in /docs (aws-powertools#2194)

Bumps squidfunk/mkdocs-material from `00f9276` to `f5c556a`.

---
updated-dependencies:
- dependency-name: squidfunk/mkdocs-material
  dependency-version: f5c556a6d30ce0c1c0df10e3c38c79bbcafdaea4b1c1be366809d0d4f6f9d57f
  dependency-type: direct:production
...

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

Author: dependabot[bot]

docs/Dockerfile

@@ -1,4 +1,4 @@
-FROM squidfunk/mkdocs-material@sha256:00f9276315990b82f5af8c47bb2b71e2c69aef9f02a08f8dffd2515f42310753
+FROM squidfunk/mkdocs-material@sha256:f5c556a6d30ce0c1c0df10e3c38c79bbcafdaea4b1c1be366809d0d4f6f9d57f
 
 COPY requirements.txt /tmp/
 RUN pip install --require-hashes -r /tmp/requirements.txt