Merge #20007

20007: release-test.yml: Add stasbourg creds r=miri64 a=MrKevinWeiss


### Contribution description

This adds creds for stasbourg needed for the `openmote-b` tests in the release specs.

### Testing procedure

Hmmm... I don't know how easy it is.  I will try to link results of the workflow from my personal fork maybe?

### Issues/PRs references

Needed for RIOT-OS/Release-Specs#289


Co-authored-by: MrKevinWeiss <weiss.kevin604@gmail.com>

.github/workflows/release-test.yml

@@ -78,11 +78,19 @@ jobs:
         ssh -oStrictHostKeyChecking=accept-new \
           ${IOTLAB_USER}@saclay.iot-lab.info exit
     - name: Fetch host key from IoT-LAB lille site
+      # Not being used in the most recent release specs but kept in for
+      # backwords compatibility
       if: ${{ matrix.pytest_mark == 'iotlab_creds' }}
       run: |
         IOTLAB_USER=$(cat ~/.iotlabrc | cut -f1 -d:)
         ssh -oStrictHostKeyChecking=accept-new \
           ${IOTLAB_USER}@lille.iot-lab.info exit
+    - name: Fetch host key from IoT-LAB stasbourg site
+      if: ${{ matrix.pytest_mark == 'iotlab_creds' }}
+      run: |
+        IOTLAB_USER=$(cat ~/.iotlabrc | cut -f1 -d:)
+        ssh -oStrictHostKeyChecking=accept-new \
+          ${IOTLAB_USER}@stasbourg.iot-lab.info exit
     - name: Checkout Release-Specs
       uses: actions/checkout@main
       with: