ci: install bnb with [test] extras to get pytest + pipefail for test steps

First run showed tests silently "passed" in 1-2 min — pytest wasn't installed
(--force-reinstall --no-deps stripped bnb's test extras) and | tee masked
the resulting exit code.

Align with the existing test-runner.yml pattern: install via the [test]
extras so pytest and other test deps come along. Also add `shell: bash -o
pipefail` to the pytest steps so pipe failures are surfaced.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Titus-von-Koeller

.github/workflows/tests-integration-nightly.yml

@@ -60,7 +60,7 @@ jobs:
       - name: Install torch + bnb (from continuous-release)
         run: |
           pip install torch==${TORCH_VERSION} --index-url ${PYPI_INDEX}
-          pip install --force-reinstall --no-deps ${BNB_WHEEL_URL}
+          pip install "bitsandbytes[test] @ ${BNB_WHEEL_URL}"
 
       - name: Install transformers and clone matching tag
         run: |
@@ -80,6 +80,7 @@ jobs:
         env:
           RUN_SLOW: "1"
           CUDA_VISIBLE_DEVICES: "0"
+        shell: bash -o pipefail {0}
         run: |
           mkdir -p ${GITHUB_WORKSPACE}/reports
           python -m pytest tests/quantization/bnb/ \
@@ -115,7 +116,7 @@ jobs:
       - name: Install torch + bnb (from continuous-release)
         run: |
           pip install torch==${TORCH_VERSION} --index-url ${PYPI_INDEX}
-          pip install --force-reinstall --no-deps ${BNB_WHEEL_URL}
+          pip install "bitsandbytes[test] @ ${BNB_WHEEL_URL}"
 
       - name: Install accelerate and clone matching tag
         run: |
@@ -135,6 +136,7 @@ jobs:
         env:
           RUN_SLOW: "1"
           CUDA_VISIBLE_DEVICES: "0"
+        shell: bash -o pipefail {0}
         run: |
           mkdir -p ${GITHUB_WORKSPACE}/reports
           python -m pytest tests/test_quantization.py \
@@ -170,7 +172,7 @@ jobs:
       - name: Install torch + bnb (from continuous-release)
         run: |
           pip install torch==${TORCH_VERSION} --index-url ${PYPI_INDEX}
-          pip install --force-reinstall --no-deps ${BNB_WHEEL_URL}
+          pip install "bitsandbytes[test] @ ${BNB_WHEEL_URL}"
 
       - name: Install peft and clone matching tag
         run: |
@@ -190,6 +192,7 @@ jobs:
         env:
           IS_GITHUB_CI: "1"
           CUDA_VISIBLE_DEVICES: "0"
+        shell: bash -o pipefail {0}
         run: |
           mkdir -p ${GITHUB_WORKSPACE}/reports
           python -m pytest \