ci: dont release on pull requests

.github/workflows/release.yml

@@ -9,23 +9,32 @@ on:
       - main
 
 jobs:
-  build_and_release:
+  compile_latex:
     runs-on: ubuntu-latest
 
     steps:
       - name: Checkout code
         uses: actions/checkout@v2
 
-      - name: Get current date
-        id: date
-        run: echo "::set-output name=date::$(date +'%Y%m%d')"
-
       - name: Compile LaTeX
         uses: hspaans/latexmk-action@v1
         with:
           format: pdf
           filename: root.tex
 
+  create_release:
+    needs: compile_latex
+    runs-on: ubuntu-latest
+    if: github.event_name == 'push'
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Get current date
+        id: date
+        run: echo "::set-output name=date::$(date +'%Y%m%d')"
+
       - name: Create Release
         id: create_release
         uses: actions/create-release@v1