Prevent NPE in GroupContext

Create codeql-analysis.yml

Merge pull request alitto#28 from alitto/bug/purge-after-channel-clos…

…ed-2

Allow concurrent calls to StopAndWait & other fixes

Fix readme badges

Update dependencies in benchmark

Merge pull request alitto#16 from alitto/feature/1.6.0

Upgrade to go v1.17

Fix flaky tests

Merge pull request alitto#9 from alitto/feature/1.5.0

Metrics, Prometheus example, Upgrade to Go 1.15 and fixes

Fix corner cases and improve benchmarks section

Fix failing test