Add chrome argument --no-sandbox for pdf creation

bin/mdshow

@@ -196,7 +196,7 @@ pdf: $(basename $(SLIDES)).pdf
 $(basename $(SLIDES)).pdf: serving build
 	pdf_size="$$($(MDSHOW_CONFIG)/reveal.js/node_modules/node-jq/bin/jq -r '.pdf_size' < $(BUILD_DIR)/config.json)"; \
 		pdf_delay="$$($(MDSHOW_CONFIG)/reveal.js/node_modules/node-jq/bin/jq -r '.pdf_delay' < $(BUILD_DIR)/config.json)"; \
-		$(MDSHOW_CONFIG)/reveal.js/node_modules/.bin/decktape -p $${pdf_delay} -s $${pdf_size} http://localhost:$(PORT)/ $@ || \
+		$(MDSHOW_CONFIG)/reveal.js/node_modules/.bin/decktape -p $${pdf_delay} -s $${pdf_size} --chrome-arg="--no-sandbox" http://localhost:$(PORT)/ $@ || \
 		echo "Failed to create $@. Is the mdshow server running? mdshow serve"
 
 # {{{1 serve