minor adjustments to Dockerfile

1 job for master in 2 minutes and 12 seconds (queued for 1 second)
Name Stage Failure
build Build
Adding new group `vivado' (1000) ...
Adding new user `vivado' (1000) with group `vivado' ...
Creating home directory `/home/vivado' ...
Copying files from `/etc/skel' ...
Removing intermediate container 0d695dab1170
---> f8cbce973a28
Step 9/18 : COPY accept-eula.sh ${PETA_RUN_FILE} /
COPY failed: stat /var/lib/docker/tmp/docker-builder965677842/global/installers/petalinux-v2019.1-final-installer.run: no such file or directory
ERROR: Job failed: exit status 1