CI: Prevent scheduled actions from running in forks

They are meant for the main repo.

.github/workflows/coverity.yml

@@ -11,6 +11,7 @@ on:
 
 jobs:
   build:
+    if: github.repository == 'sipwise/rtpengine'
     runs-on: ubuntu-24.04
 
     env:

.github/workflows/debpkg.yml

@@ -8,6 +8,7 @@ on:
 
 jobs:
   build-deb-bookworm:
+    if: github.event_name != 'schedule' || github.repository == 'sipwise/rtpengine'
     runs-on: ubuntu-latest
     name: Debian pipeline for bookworm
 
@@ -31,6 +32,7 @@ jobs:
         path: '*.buildinfo'
 
   build-deb-sid:
+    if: github.event_name != 'schedule' || github.repository == 'sipwise/rtpengine'
     runs-on: ubuntu-latest
     name: Debian pipeline for sid
 

.github/workflows/shellcheck.yml

@@ -8,6 +8,7 @@ on:
 
 jobs:
   test:
+    if: github.event_name != 'schedule' || github.repository == 'sipwise/rtpengine'
     runs-on: ubuntu-latest
 
     steps:

.github/workflows/unit-tests.yml

@@ -8,6 +8,7 @@ on:
 
 jobs:
   test:
+    if: github.event_name != 'schedule' || github.repository == 'sipwise/rtpengine'
     runs-on: ubuntu-24.04
     name: Run unit tests