Migrate CI setup to GitHub Actions, also publish to GHCR (#199)

* Run tests in GitHub actions

* Do not try to allocate a pseudo TTY when running compose commands

* Try hard disabling TTY allocation

* Use compose plugin

* Test scripts shall not try to allocate a TTY

* Pass correct base version

* Check whether env var is even needed

* Stop running tests in CircleCI

* Run releases from GitHub actions as well

* Manually construct tags to be pushed on release

test/ssh/run.sh

@@ -17,7 +17,7 @@ sleep 5
 
 expect_running_containers 3
 
-docker run --rm -it \
+docker run --rm \
   -v ssh_backup_data:/ssh_data \
   alpine \
   ash -c 'tar -xvf /ssh_data/test-hostnametoken.tar.gz -C /tmp && test -f /tmp/backup/app_data/offen.db'
@@ -32,7 +32,7 @@ sleep 5
 
 docker compose exec backup backup
 
-docker run --rm -it \
+docker run --rm \
   -v ssh_backup_data:/ssh_data \
   alpine \
   ash -c '[ $(find /ssh_data/ -type f | wc -l) = "1" ]'