chore: bump squidfunk/mkdocs-material in /docs (#2144)

Bumps squidfunk/mkdocs-material from `209b62d` to `86d21da`.

---
updated-dependencies:
- dependency-name: squidfunk/mkdocs-material
  dependency-version: 86d21da4f45f16e30774bf911e5b4795da13ce0cd197dbf8d3d059f256b2cc37
  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@sha256:209b62dd9530163cc5cf9a49853b5bb8570ffb3f3b5fe4eadc1d319bbda5ce2f
+FROM squidfunk/mkdocs-material@sha256:86d21da4f45f16e30774bf911e5b4795da13ce0cd197dbf8d3d059f256b2cc37
 
 COPY requirements.txt /tmp/
 RUN pip install --require-hashes -r /tmp/requirements.txt