Run packer build biweekly

This runs the build more often so we can continue to debug any remaining
issues, and ensures that we release a new image on the 15th of this
month (since it was broken on the 1st)

.circleci/config.yml

@@ -1265,10 +1265,10 @@ workflows:
       - publish-dockerhub:
           name: publish-dockerhub-nightly
           tag: nightly
-  monthly:
+  biweekly:
     triggers:
       - schedule:
-          cron: "0 0 1 * *"
+          cron: "0 0 1,15 * *"
           filters:
             branches:
               only:

.circleci/template.yml

@@ -990,10 +990,10 @@ workflows:
       - publish-dockerhub:
           name: publish-dockerhub-nightly
           tag: nightly
-  monthly:
+  biweekly:
     triggers:
       - schedule:
-          cron: "0 0 1 * *"
+          cron: "0 0 1,15 * *"
           filters:
             branches:
               only: