Revert "Disable all jobs for testing"

This reverts commit c7887978a35db2b5c0113269268cfc71775aeef2.
diff --git a/mbed-tls-pr-merge.yaml b/mbed-tls-pr-merge.yaml
index 7513ab9..278e206 100644
--- a/mbed-tls-pr-merge.yaml
+++ b/mbed-tls-pr-merge.yaml
@@ -2,7 +2,7 @@
     name: mbed-tls-pr-merge
     description: 'Job for testing PRs merged with the target branch head'
     project-type: multibranch
-    disabled: true
+    disabled: false
     prune-dead-branches: true
     days-to-keep: 60
     num-to-keep: 1000