restrict actions a bit more

.github/workflows/checks.yml

@@ -7,9 +7,8 @@ permissions:
 
 jobs:
   build:
-
+    if: github.repository == 'CGAL/cgal' || github.event_name != 'push'
     runs-on: ubuntu-latest
-    
     steps:
     - uses: actions/checkout@v4
     - name: install dependencies
@@ -17,7 +16,7 @@ jobs:
         .github/install.sh
         set -x
         sudo apt-get update && sudo apt-get install -y graphviz ssh bibtex2html
-        sudo pip install lxml 
+        sudo pip install lxml
         sudo pip install 'pyquery==1.4.1' # it seems to be the last py2 compatible version
         wget --no-verbose -O doxygen_exe https://cgal.geometryfactory.com/~cgaltest/doxygen_1_8_13_patched/doxygen
         sudo mv doxygen_exe /usr/bin/doxygen

.github/workflows/cmake-all.yml

@@ -7,9 +7,8 @@ permissions:
 
 jobs:
   cmake-testsuite:
-
+    if: github.repository == 'CGAL/cgal' || github.event_name != 'push'
     runs-on: ubuntu-latest
-
     steps:
     - uses: actions/checkout@v4
     - name: install dependencies
@@ -21,9 +20,8 @@ jobs:
         ctest -L Installation -j $(getconf _NPROCESSORS_ONLN)
 
   cmake-testsuite-with-qt:
-
+    if: github.repository == 'CGAL/cgal' || github.event_name != 'push'
     runs-on: ubuntu-latest
-
     steps:
     - uses: actions/checkout@v4
     - name: install dependencies