Use openci-testing branch

Change-Id: I20c24374b2ba46e707b71eb8ec2e804ea67b0ccb
diff --git a/mbed-tls-framework-multibranch.yaml b/mbed-tls-framework-multibranch.yaml
index 9433f84..7cccf15 100644
--- a/mbed-tls-framework-multibranch.yaml
+++ b/mbed-tls-framework-multibranch.yaml
@@ -27,7 +27,7 @@
                       </traits>
                     </scm>
                   </retriever>
-                  <defaultVersion>main</defaultVersion>
+                  <defaultVersion>dev/dgreen-arm/openci-testing</defaultVersion>
                   <implicit>true</implicit>
                   <allowVersionOverride>true</allowVersionOverride>
                   <includeInChangesets>true</includeInChangesets>