chore(ci): migrate Scheduled workflow to Scheduled pipeline (#132)

Author: bednar

.circleci/config.yml

@@ -157,6 +157,9 @@ jobs:
 workflows:
   version: 2
   build:
+    when:
+      not:
+        equal: [ scheduled_pipeline, << pipeline.trigger_source >> ]
     jobs:
       - tests-php:
           name: php-7.4
@@ -182,12 +185,7 @@ workflows:
       - check-code-style
 
   nightly:
-    triggers:
-      - schedule:
-          cron: "0 0 * * *"
-          filters:
-            branches:
-              only:
-                - master
+    when:
+      equal: [ scheduled_pipeline, << pipeline.trigger_source >> ]
     jobs:
       - tests-php