ci(docs): Fix cached mdbook version overwrite

docs/.gitlab-ci.yaml

@@ -24,7 +24,7 @@ build-docs:
     MDBOOK_VERSION: v0.4.37
   before_script:
     - export PATH="$PATH:$CARGO_HOME/bin"
-    - mdbook --version | grep "$MDBOOK_VERSION" || cargo install --version "${MDBOOK_VERSION//v}" mdbook
+    - mdbook --version | grep "$MDBOOK_VERSION" || cargo install --version "${MDBOOK_VERSION//v}" --force mdbook
   script:
     - mdbook build docs
   rules:
@@ -63,4 +63,4 @@ upload-docs:
           - images/**/README.md
           - charts/**/README.md
   tags:
-    - kubernetes
+    - kubernetes
\ No newline at end of file