Add torchcodec to the list of nightly dispatch options (#5823)

My miss in reviewing #5814,
having torchcodec in the list of options will allow folks to test the
nightly build manually.

.github/workflows/trigger_nightly.yml

@@ -21,6 +21,7 @@ on:
           - fbgemm
           - executorch
           - torchtune
+          - torchcodec
           - all
 jobs:
   trigger: