Don't build release image on PRs

When we push to our own organization this would trigger. As we only care
for the push target in our own repo this is much easier. If someone
would for they would need to change this but that is up to them.

Author: Michael Vasseur

.github/workflows/build-contributor-container-release.yml

@@ -4,13 +4,12 @@ name: 'Build Contributor container (Release)'
 
 on:
   push:
-  pull_request_target:
     branches:
       - main
 
 jobs:
   release-contributor:
-    if: ${{ github.repository == 'domjudge/domjudge-packaging' && github.ref == 'refs/heads/main' }} 
+    if: ${{ github.repository == 'domjudge/domjudge-packaging' }}
     runs-on: ubuntu-latest
     steps:
       - name: Checkout

.github/workflows/build-domjudge-container-release.yml

@@ -2,7 +2,6 @@ name: 'Build domjudge container (Release)'
 
 on:
   push:
-  pull_request_target:
     branches:
       - main
 
@@ -12,7 +11,7 @@ env:
 
 jobs:
   release-domjudge:
-    if: ${{ github.repository == 'domjudge/domjudge-packaging' && github.ref == 'refs/heads/main' }}
+    if: ${{ github.repository == 'domjudge/domjudge-packaging' }}
     runs-on: ubuntu-latest
     steps:
       - name: Checkout

.github/workflows/build-gitlab-container-release.yml

@@ -7,7 +7,7 @@ on:
 
 jobs:
   build-gitlab:
-    if: ${{ github.repository == 'domjudge/domjudge-packaging' && github.ref == 'refs/heads/main' }} 
+    if: ${{ github.repository == 'domjudge/domjudge-packaging' }}
     name: Build GitLab image
     runs-on: ubuntu-latest
     permissions: