[CI] Temporarily pin paddlepaddle-gpu to 3.5.0.dev20260601 (#7987)

Author: EmmonsCurse

.github/workflows/_unit_test_coverage.yml

@@ -224,7 +224,7 @@ jobs:
           git config --global --add safe.directory /workspace/FastDeploy
           cd FastDeploy
           git diff origin/${BASE_REF}..HEAD --unified=0 > diff.txt
-          python -m pip install --pre paddlepaddle-gpu -i https://www.paddlepaddle.org.cn/packages/nightly/cu126/
+          python -m pip install paddlepaddle-gpu==3.5.0.dev20260601 -i https://www.paddlepaddle.org.cn/packages/nightly/cu126/
           pip config set global.extra-index-url https://mirrors.tuna.tsinghua.edu.cn/pypi/web/simple
 
           python -m pip install -r scripts/unittest_requirement.txt