chore(deps): update github actions (major) (#1640)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/checkout](https://redirect.github.com/actions/checkout) |
action | major | `v4` -> `v5` |
| [actions/setup-node](https://redirect.github.com/actions/setup-node) |
action | major | `v5` -> `v6` |
| [actions/setup-node](https://redirect.github.com/actions/setup-node) |
action | major | `v4` -> `v6` |

---

### Release Notes

<details>
<summary>actions/checkout (actions/checkout)</summary>

### [`v5`](https://redirect.github.com/actions/checkout/compare/v4...v5)

[Compare
Source](https://redirect.github.com/actions/checkout/compare/v4...v5)

</details>

<details>
<summary>actions/setup-node (actions/setup-node)</summary>

###
[`v6`](https://redirect.github.com/actions/setup-node/compare/v5...v6)

[Compare
Source](https://redirect.github.com/actions/setup-node/compare/v5...v6)

</details>

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined),
Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you
are satisfied.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the
rebase/retry checkbox.

👻 **Immortal**: This PR will be recreated if closed unmerged. Get
[config
help](https://redirect.github.com/renovatebot/renovate/discussions) if
that's undesired.

---

- [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check
this box

---

This PR was generated by [Mend Renovate](https://mend.io/renovate/).
View the [repository job
log](https://developer.mend.io/github/googleapis/genai-toolbox).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0MS4xMzEuOSIsInVwZGF0ZWRJblZlciI6IjQxLjE0My4xIiwidGFyZ2V0QnJhbmNoIjoibWFpbiIsImxhYmVscyI6W119-->

Co-authored-by: Wenxin Du <117315983+duwenxin99@users.noreply.github.com>

.github/workflows/deploy_dev_docs.yaml

@@ -51,7 +51,7 @@ jobs:
           extended: true
 
       - name: Setup Node
-        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
+        uses: actions/setup-node@2028fbc5c25fe9cf00d9f06a71cc4710d4507903 # v6
         with:
           node-version: "22"
 

.github/workflows/deploy_previous_version_docs.yaml

@@ -30,14 +30,14 @@ jobs:
 
     steps:
       - name: Checkout main branch (for latest templates and theme)
-        uses: actions/checkout@08eba0b27e820071cde6df949e0beb9ba4906955 # v4
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
         with:
           ref: 'main'
           submodules: 'recursive'
           fetch-depth: 0
 
       - name: Checkout old content from tag into a temporary directory
-        uses: actions/checkout@08eba0b27e820071cde6df949e0beb9ba4906955 # v4
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
         with:
           ref: ${{ github.event.inputs.version_tag }}
           path: 'old_version_source' # Checkout into a temp subdir
@@ -57,7 +57,7 @@ jobs:
         with:
           hugo-version: "0.145.0"
           extended: true
-      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
+      - uses: actions/setup-node@2028fbc5c25fe9cf00d9f06a71cc4710d4507903 # v6
         with:
           node-version: "22"
 

.github/workflows/deploy_versioned_docs.yaml

@@ -30,7 +30,7 @@ jobs:
       cancel-in-progress: false
     steps:
       - name: Checkout Code at Tag
-        uses: actions/checkout@08eba0b27e820071cde6df949e0beb9ba4906955 # v4
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
         with:
           ref: ${{ github.event.release.tag_name }}
 
@@ -44,7 +44,7 @@ jobs:
           extended: true
 
       - name: Setup Node
-        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
+        uses: actions/setup-node@2028fbc5c25fe9cf00d9f06a71cc4710d4507903 # v6
         with:
           node-version: "22"
 

.github/workflows/docs_deploy.yaml

@@ -50,7 +50,7 @@ jobs:
           extended: true
 
       - name: Setup Node
-        uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5
+        uses: actions/setup-node@2028fbc5c25fe9cf00d9f06a71cc4710d4507903 # v6
         with:
           node-version: "22"
 

.github/workflows/docs_preview_deploy.yaml

@@ -62,7 +62,7 @@ jobs:
           extended: true
 
       - name: Setup Node
-        uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5
+        uses: actions/setup-node@2028fbc5c25fe9cf00d9f06a71cc4710d4507903 # v6
         with:
           node-version: "22"