ci: add color to git diff

Author: consideRatio

.github/workflows/test.yml

@@ -95,7 +95,7 @@ jobs:
             # Use chartpress to create the helm chart and build its images
             helm dependency update ./helm-chart/binderhub
             (cd helm-chart && chartpress)
-            git --no-pager diff
+            git --no-pager diff --color=always
 
       - name: Validate the chart against the k8s API
         if: matrix.test == 'helm'