ci(doc): make renovatebot bump locked mdbook

Author: rami3l

.github/renovate.json

@@ -1,7 +1,8 @@
 {
     "$schema": "https://docs.renovatebot.com/renovate-schema.json",
     "extends": [
-        "config:recommended"
+        "config:recommended",
+        "customManagers:githubActionsVersions"
     ],
     "labels": [
         "dependencies"

.github/workflows/ci.yaml

@@ -1527,6 +1527,7 @@ jobs:
       - name: Install mdbook
         uses: taiki-e/install-action@v2
         env:
+          # renovate: datasource=crates depName=mdbook
           MDBOOK_VERSION: "0.4.43"
         with:
           tool: mdbook@${{ env.MDBOOK_VERSION }}

ci/actions-templates/test-docs-template.yaml

@@ -14,6 +14,7 @@ jobs: # skip-all
       - name: Install mdbook
         uses: taiki-e/install-action@v2
         env:
+          # renovate: datasource=crates depName=mdbook
           MDBOOK_VERSION: "0.4.43"
         with:
           tool: mdbook@${{ env.MDBOOK_VERSION }}