Fix: Bumping core to v6.64.0 automatically via 'frameworkpullrequest' Github action (#3695)

Co-authored-by: oliverfoster <[email protected]>

Author: oliverfoster

.gitmodules

@@ -2,4 +2,4 @@
   path = src/core
   branch = master
   url = https://github.com/adaptlearning/adapt-contrib-core
-  installBranch = v6.63.2
+  installBranch = v6.64.0