[Code scan] Pin privileged pull_request_target action or replace it with first-party API

[njzjz]

This issue was found by a Codex global scan of the repository at commit 19f9265.

The label-removal workflow runs on pull_request_target, grants pull-requests: write, and invokes a third-party action by a mutable tag:

deepmd-gnn/.github/workflows/remove_test_cuda_label.yml

Lines 4 to 16 in 19f9265

	pull_request_target:
	types:
	- labeled
	jobs:
	remove_label:
	permissions:
	contents: read
	pull-requests: write
	runs-on: ubuntu-latest
	if: github.repository_owner == 'deepmodeling' && github.event.label.name == 'Test CUDA'
	steps:
	- uses: actions-ecosystem/action-remove-labels@v1

This workflow does not check out or execute fork code, so the risk is much narrower than the common pull_request_target anti-pattern. Still, a mutable third-party action in a privileged workflow is a supply-chain risk.

Suggested fix: replace the action with a small gh api / GitHub Script step using the built-in token, or pin actions-ecosystem/action-remove-labels to a reviewed commit SHA instead of @v1.