ci: Address Zizimor Findings

[lqiu96]

Fixes: #13925

Output of zizmor --fix=all --gh-token=$(gh auth token) ${YOUR_GH_DIRECTORY}/.github/workflows/

From: go/github-zizmor-help

[gemini-code-assist]

Note

Gemini is unable to generate a review for this pull request due to the file types involved not being currently supported.

[lqiu96]

Error:

Error: Found 1 findings for mandatory checks that must always succeed.
Error: unpinned action reference: action is not pinned to a hash (required by blanket policy)
=========================================
CRITICAL: The following mandatory checks failed:
- zizmor/unpinned-uses at line 104 of .github/workflows/librarian_generation_check.yaml: unpinned action reference: action is not pinned to a hash (required by blanket policy)
=========================================
Blocking due to failed mandatory checks. These checks cannot be ignored.

[sonarqubecloud]

Quality Gate passed for 'gapic-generator-java-root'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[sonarqubecloud]

Quality Gate passed for 'gapic-generator-java-root'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud