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/azure/run.sh

@@ -6,12 +6,12 @@ cd "$(dirname "$0")"
 . ../util.sh
 current_test=$(basename $(pwd))
 
-docker-compose up -d
+docker compose up -d
 sleep 5
 
 # A symlink for a known file in the volume is created so the test can check
 # whether symlinks are preserved on backup.
-docker-compose exec backup backup
+docker compose exec backup backup
 
 sleep 5
 
@@ -29,12 +29,12 @@ pass "Found relevant files in untared remote backups."
 BACKUP_RETENTION_DAYS="0" docker-compose up -d
 sleep 5
 
-docker-compose exec backup backup
+docker compose exec backup backup
 
-docker-compose run --rm az_cli \
+docker compose run --rm az_cli \
   az storage blob download -f /dump/test.tar.gz -c test-container -n path/to/backup/test.tar.gz
 test -f ./local/test.tar.gz
 
 pass "Remote backups have not been deleted."
 
-docker-compose down --volumes
+docker compose down --volumes