let it decide on headless

Author: pahjbo

.github/workflows/site.yml

@@ -34,7 +34,7 @@ jobs:
         run: |
           echo "$THISDIR/bin" >> "$GITHUB_PATH"
           curl -L -o plantuml.jar https://github.com/plantuml/plantuml/releases/download/v1.2026.1/plantuml-1.2026.1.jar
-          echo "$JAVA_HOME/bin/java -Djava.awt.headless=true -jar $THISDIR/bin/plantuml.jar $@" >plantuml
+          echo "$JAVA_HOME/bin/java -jar $THISDIR/bin/plantuml.jar $@" >plantuml
           chmod +x plantuml
         working-directory: ./bin
       - name: try plantuml
@@ -55,3 +55,4 @@ jobs:
         with:
           run: ./gradlew doSite
 
+