CI: check out RobustToolbox so nightly walkthroughs pass (weighted_corrcoef dep)

.github/workflows/tests-walkthroughs.yml

@@ -39,6 +39,17 @@ jobs:
           repository: canlab/CANlab_help_examples
           path: CANlab_help_examples
 
+      - name: Checkout RobustToolbox
+        # Provides weighted_corrcoef (Robust_stats_functions/), a dependency of
+        # plot_correlation_samefig's robust branch used by the regression
+        # walkthrough. A normal canlab_toolbox_setup install adds this sibling
+        # repo to the path; CI must too, or walkthrough 5 errors with
+        # "Undefined function 'weighted_corrcoef'".
+        uses: actions/checkout@v4
+        with:
+          repository: canlab/RobustToolbox
+          path: RobustToolbox
+
       - name: Clone SPM25
         run: git clone --depth=1 --branch 25.01.02 https://github.com/spm/spm.git "${GITHUB_WORKSPACE}/spm"
 
@@ -59,6 +70,7 @@ jobs:
             addpath(genpath('CanlabCore'));
             addpath(genpath('Neuroimaging_Pattern_Masks'));
             addpath(genpath('CANlab_help_examples'));
+            addpath(genpath('RobustToolbox'));
             % NB: addpath, not genpath — SPM compat shims would shadow
             % MATLAB builtins; see test.yml for the same rationale.
             addpath('spm');