Fix permission errors in Dockerfile and update docker-compose.yml

Dockerfile

@@ -15,6 +15,8 @@ COPY src ./src
 COPY bot.properties.example bot.properties ./
 COPY startup.sh ./
 
+RUN ["chmod", "+x", "./mvnw"]
 RUN ./mvnw install
 
+RUN ["chmod", "+x", "./startup.sh"]
 CMD ["./startup.sh"]