Implement automatic release in Github Actions

Build tags in CI

Bump version to 5.0.4

Nullability errors as warnings

Because of SDK changes

Bump version to 6.0.0-preview2

Ignore test Bug3466 because of flakiness

(cherry picked from commit 37b3257)

Fixed exception message for SASL Continue error (npgsql#3473)

(cherry picked from commit d413846)

Merge branch 'hotfix/5.0.2' into stable

Bump version to 5.0.1.1

Switch to official Microsoft setup-msbuild action