chore(docs): Add concurrency group to docs deployment workflows (#1696)

## Description

This PR adds a concurrency group to both the in-development docs and
versioned docs deployment workflows.
On the 0.17.0 release, both the workflows were run at the same time
causing a deployment issue and the second workflow (versioned doc
deploy) to fail (due to a git push error as they are both attempting to
push into the versioned-gh-pages branch). This PR adds both the
workflows into the same concurrency group to make sure the first
deployment is completed before running the second one.

## PR Checklist

> Thank you for opening a Pull Request! Before submitting your PR, there
are a
> few things you can do to make sure it goes smoothly:

- [x] Make sure you reviewed

[CONTRIBUTING.md](https://github.com/googleapis/genai-toolbox/blob/main/CONTRIBUTING.md)
- [ ] Make sure to open an issue as a

[bug/issue](https://github.com/googleapis/genai-toolbox/issues/new/choose)
  before writing your code! That way we can discuss the change, evaluate
  designs, and agree on the general idea
- [x] Ensure the tests and linter pass
- [x] Code coverage does not decrease (if any source code was changed)
- [x] Appropriate docs were updated (if necessary)
- [x] Make sure to add `!` if this involve a breaking change

🛠️ Fixes #<issue_number_goes_here>

.github/workflows/deploy_dev_docs.yaml

@@ -4,7 +4,7 @@
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
-#      http://www.apache.org/licenses/LICENSE-2.0
+#     http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
@@ -35,9 +35,10 @@ jobs:
     defaults:
       run:
         working-directory: .hugo
+    # This shared concurrency group ensures only one docs deployment runs at a time.
     concurrency:
-      group: ${{ github.workflow }}-${{ github.ref }}
-      cancel-in-progress: true
+      group: docs-deployment
+      cancel-in-progress: false
     steps:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
         with:
@@ -81,4 +82,4 @@ jobs:
           publish_dir: ./.hugo/staging
           publish_branch: versioned-gh-pages
           keep_files: true
-          commit_message: "deploy: ${{ github.event.head_commit.message }}"
+          commit_message: "deploy: ${{ github.event.head_commit.message }}"

.github/workflows/deploy_versioned_docs.yaml

@@ -4,7 +4,7 @@
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
-#      http://www.apache.org/licenses/LICENSE-2.0
+#     http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
@@ -24,6 +24,10 @@ on:
 jobs:
   deploy:
     runs-on: ubuntu-24.04
+    # This shared concurrency group ensures only one docs deployment runs at a time.
+    concurrency:
+      group: docs-deployment
+      cancel-in-progress: false
     steps:
       - name: Checkout Code at Tag
         uses: actions/checkout@08eba0b27e820071cde6df949e0beb9ba4906955 # v4
@@ -83,4 +87,4 @@ jobs:
           publish_branch: versioned-gh-pages
           keep_files: true
           allow_empty_commit: true
-          commit_message: "deploy: docs to root for ${{ env.VERSION }}"
+          commit_message: "deploy: docs to root for ${{ env.VERSION }}"