cifuzz.yml: Run when code is pushed to develop or main etc.

Matches main.yml on: statement for push.

on: pull_request removed so that it is not run for every PR, just the
develop, main and release branches.

.github/workflows/cifuzz.yml

@@ -1,5 +1,13 @@
 name: CIFuzz
-on: [pull_request]
+
+on:
+  push:
+    branches:
+      - main
+      - develop
+      - release-*
+      - gh-workflows
+
 jobs:
   Fuzzing:
     runs-on: ubuntu-latest