Release v1.7.3, re opentracing-contrib#569

Release v1.7.2, re opentracing-contrib#562

Release v1.7.1, re opentracing-contrib#549

Update README.md [skip ci]

Fix purge opentracing-adapter

Release v1.6.0, re opentracing-contrib#491

Update CHANGELOG.md, re opentracing-contrib#443 [skip ci]

Release v1.5.8, re opentracing-contrib#416

Release v1.5.7, re opentracing-contrib#383

Release v1.5.6, re opentracing-contrib#360