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/cli/run.sh

@@ -48,7 +48,7 @@ docker run --rm \
   --entrypoint backup \
   offen/docker-volume-backup:${TEST_VERSION:-canary}
 
-docker run --rm -it \
+docker run --rm \
   -v backup_data:/data alpine \
   ash -c 'tar -xvf /data/backup/test.tar.gz && test -f /backup/app_data/offen.db && test -d /backup/empty_data'