chore(deps): bump squidfunk/mkdocs-material in /docs (#1991)

Bumps squidfunk/mkdocs-material from `9aad7af` to `a4a2029`.

---
updated-dependencies:
- dependency-name: squidfunk/mkdocs-material
  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

@@ -1,5 +1,5 @@
 # version 9.5.2
-FROM squidfunk/mkdocs-material@sha256:9aad7af2f62950826f57928e984ea8aa77a561f67b7f5fc251ced67d52a2a5fe
+FROM squidfunk/mkdocs-material@sha256:a4a2029fdf524f0c727852e492cd2bbae30cc9471959da60d7dc46bf565a521b
 
 ADD requirements.txt /tmp/
 RUN pip install --require-hashes -r /tmp/requirements.txt