ci: raise timeout on ics-light-client-attack

This single job was failing due to timeout. Bumping its timeout.
We could also switch to a faster runner, but a separate job takes ~1h,
which is really where we should focus attention.

.github/workflows/misbehaviour.yml

@@ -88,7 +88,7 @@ jobs:
 
   ics-light-client-attack:
     runs-on: ubuntu-20.04
-    timeout-minutes: 20
+    timeout-minutes: 60
     strategy:
       fail-fast: false
       matrix: