tf-m-code-coverage: Run once a week on Saturday

Based on discussion in https://linaro.atlassian.net/browse/TFC-512

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I3db93e01549cf4c3fdbdbfe834674a4b6ff8b56b
diff --git a/tf-m-code-coverage.yaml b/tf-m-code-coverage.yaml
index 012f5bb..878e5d5 100644
--- a/tf-m-code-coverage.yaml
+++ b/tf-m-code-coverage.yaml
@@ -17,7 +17,7 @@
           days-to-keep: 90
           num-to-keep: 45
     triggers:
-      - timed: 'H 19 */2 * *'
+      - timed: 'H 19 * * 6'
     parameters:
       - string:
           name: 'FILTER_GROUP'