ci(docs): Use pinned version

docs/.gitlab-ci.yaml

 stages:
     - build
 
-pages:
+build-docs:
   stage: build
   image: docker.io/library/rust
   variables:
     CARGO_HOME: $CI_PROJECT_DIR/cargo
+    # renovate: datasource=github-releases depName=rust-lang/mdBook
+    MDBOOK_VERSION: v0.4.36
   before_script:
     - export PATH="$PATH:$CARGO_HOME/bin"
-    - mdbook --version || cargo install mdbook
+    - mdbook --version || cargo install --version "${MDBOOK_VERSION//v}" mdbook
   script:
     - mdbook build docs -d public
   rules:
@@ -23,7 +25,7 @@ pages:
   tags:
     - kubernetes
 
-upload:
+upload-docs:
   stage: release
   image:
     name: docker.io/minio/mc

images/tools/Earthfile

@@ -138,8 +138,8 @@ mdbook:
     # mdbook CLI cache
     FROM ../mirror+fedora
 
-    # renovate: datasource=github-releases depName=kubernetes-sigs/krew
-    ARG MDBOOK_VERSION=v0.4.18
+    # renovate: datasource=github-releases depName=rust-lang/mdBook
+    ARG MDBOOK_VERSION=v0.4.36
     ENV MDBOOK_VERSION=${MDBOOK_VERSION}
 
     RUN curl -L "https://github.com/rust-lang/mdBook/releases/download/${MDBOOK_VERSION}/mdbook-${MDBOOK_VERSION}-x86_64-unknown-linux-gnu.tar.gz" | tar xvzf - mdbook \