Update renovate/renovate Docker tag to v43.173.3

Author: govuk-ci

charts/renovate/templates/cronjob.yaml

@@ -22,7 +22,7 @@ spec:
           serviceAccountName: {{ $.Values.serviceAccount.name }}
           containers:
             - name: renovate
-              image: renovate/renovate:43.170.20
+              image: renovate/renovate:43.173.3
               env:
                 - name: RENOVATE_PLATFORM
                   value: github