Merge branch 'hotfix/2.2.4'

Merge pull request npgsql#880 from roji/preview5

Port to 3.0.0-preview5

Merge branch 'preview4' into dev

Merge pull request npgsql#844 from roji/preview3

Sync with EF Core 3.0.0 preview3

Bump version to 3.0.0

Merge branch 'dev' into master

Release 2.2.0

Fix Appveyor release tag detection

Merge branch 'hotfix/2.1.2'

Merge branch 'hotfix/2.1.1.1'

Merge branch 'hotfix/2.1.1'