chore: set retention-days to limit storage

https://github.blog/changelog/2020-10-08-github-actions-ability-to-change-retention-days-for-artifacts-and-logs/

Author: danielpeintner

.github/workflows/gradle.yml

@@ -48,18 +48,22 @@ jobs:
       with:
         name: hello-fx-jdk${{ matrix.java }}-${{ matrix.os }}-exe
         path: build/jpackage/*.exe
+        retention-days: 30
     - name: Upload MSI as an artifact
       uses: actions/upload-artifact@v2
       with:
         name: hello-fx-jdk${{ matrix.java }}-${{ matrix.os }}-msi
         path: build/jpackage/*.msi
+        retention-days: 30
     - name: Upload DEB as an artifact
       uses: actions/upload-artifact@v2
       with:
         name: hello-fx-jdk${{ matrix.java }}-${{ matrix.os }}-deb
         path: build/jpackage/*.deb
+        retention-days: 30
     - name: Upload RPM as an artifact
       uses: actions/upload-artifact@v2
       with:
         name: hello-fx-jdk${{ matrix.java }}-${{ matrix.os }}-rpm
         path: build/jpackage/*.rpm
+        retention-days: 30