Yep, I had this issue, it was only after I did this, that it somehow refreshed the repo.
curl -sS https://packages.gitlab.com/install/repositories/gitlab/gitlab-ce/script.deb.sh | sudo bash
as usually when I did apt-get upgrade I would get the updated packages, but I got to 12.9.2 and then it stopped for ages. In the beginning I figured it was because of coronavirus and work had stopped but only after about six months, I decided to check and found a load of versions had been released. As an off-chance, I ran that command as if I was installing the repo for the first time, and then suddenly gitlab-ce became available to download.
You have to be careful though, since if you attempt apt-get upgrade now, you will get a 13.3.x release - hence why you have to do the command:
apt-get update
apt-get install gitlab-ce=12.9.3-ce.0
once the upgrade has finished, run the following command to make sure no background migrations are running:
gitlab-rails runner -e production 'puts Gitlab::BackgroundMigration.remaining'
do this after every upgrade The value returned must be a zero before you continue with another upgrade. The reason for doing it this way is because in a 12.10.x release, postgresql is upgraded to 11.7 and in later releases postgresql 10.x doesn’t exist. So to go higher than 12.10.x you need to be on postgresql 11.7 first, and then you can start thinking about moving to 13.x.x.
Below is my upgrade process from the bash history command:
root@repo:~# history | grep -i apt | grep -i install
1525 apt-get install gitlab-ce=12.9.3-ce.0
1535 apt-get install gitlab-ce=12.9.4-ce.0
1537 apt-get install gitlab-ce=12.9.5-ce.0
1539 apt-get install gitlab-ce=12.9.7-ce.0
1541 apt-get install gitlab-ce=12.9.8-ce.0
1543 apt-get install gitlab-ce=12.9.9-ce.0
1545 apt-get install gitlab-ce=12.9.10-ce.0
1549 apt-get install gitlab-ce=12.10.0-ce.0
1559 apt-get install gitlab-ce=12.10.1-ce.0
1562 apt-get install gitlab-ce=12.10.2-ce.0
1565 apt-get install gitlab-ce=12.10.3-ce.0
1568 apt-get install gitlab-ce=12.10.5-ce.0
1571 apt-get install gitlab-ce=12.10.6-ce.0
1574 apt-get install gitlab-ce=12.10.7-ce.0
1577 apt-get install gitlab-ce=12.10.8-ce.0
1580 apt-get install gitlab-ce=12.10.9-ce.0
1583 apt-get install gitlab-ce=12.10.10-ce.0
1586 apt-get install gitlab-ce=12.10.11-ce.0
1589 apt-get install gitlab-ce=12.10.12-ce.0
1592 apt-get install gitlab-ce=12.10.13-ce.0
1595 apt-get install gitlab-ce=12.10.14-ce.0
1689 apt-get install gitlab-ce=13.0.0-ce.0
1692 apt-get install gitlab-ce=13.0.1-ce.0
1695 apt-get install gitlab-ce=13.0.3-ce.0
1698 apt-get install gitlab-ce=13.0.4-ce.0
1701 apt-get install gitlab-ce=13.0.5-ce.0
1704 apt-get install gitlab-ce=13.0.6-ce.0
1707 apt-get install gitlab-ce=13.0.7-ce.0
1710 apt-get install gitlab-ce=13.0.8-ce.0
1713 apt-get install gitlab-ce=13.0.9-ce.0
1716 apt-get install gitlab-ce=13.0.10-ce.0
1719 apt-get install gitlab-ce=13.0.12-ce.0
1722 apt-get install gitlab-ce=13.0.13-ce.0
1725 apt-get install gitlab-ce=13.0.14-ce.0
1823 apt-get install gitlab-ce=13.1.0-ce.0
1826 apt-get install gitlab-ce=13.1.1-ce.0
1829 apt-get install gitlab-ce=13.1.2-ce.0
1832 apt-get install gitlab-ce=13.1.3-ce.0
1835 apt-get install gitlab-ce=13.1.4-ce.0
1838 apt-get install gitlab-ce=13.1.5-ce.0
1841 apt-get install gitlab-ce=13.1.6-ce.0
1843 apt-get install gitlab-ce=13.1.7-ce.0
1845 apt-get install gitlab-ce=13.1.8-ce.0
1847 apt-get install gitlab-ce=13.1.9-ce.0
1859 apt-get install gitlab-ce=13.1.10-ce.0
1861 apt-get install gitlab-ce=13.1.11-ce.0
1863 apt-get install gitlab-ce=13.2.0-ce.0
1865 apt-get install gitlab-ce=13.2.1-ce.0
1867 apt-get install gitlab-ce=13.2.2-ce.0
1869 apt-get install gitlab-ce=13.2.3-ce.0
1871 apt-get install gitlab-ce=13.2.4-ce.0
1873 apt-get install gitlab-ce=13.2.5-ce.0
1875 apt-get install gitlab-ce=13.2.6-ce.0
1877 apt-get install gitlab-ce=13.2.7-ce.0
1879 apt-get install gitlab-ce=13.2.8-ce.0
1881 apt-get install gitlab-ce=13.2.9-ce.0
1884 apt-get install gitlab-ce=13.3.0-ce.0
1885 apt-get install gitlab-ce=13.3.0-ce.1
1888 apt-get install gitlab-ce=13.3.1-ce.0
1890 apt-get install gitlab-ce=13.3.2-ce.0
1892 apt-get install gitlab-ce=13.3.3-ce.0
1894 apt-get install gitlab-ce=13.3.4-ce.0
considering the amount of upgrades I did all this split over a few days, as in total took me about 8 hours to go through all that. Each upgrade takes approx 5 - 7 mins including download time over a 200mbps connection. Maybe it was possible to do it more efficiently, but I preferred the safer route by running all of them until I got to the latest.
As of today, latest is 13.3.6.