Remove OmegaConf 2.0 deprecated APIs

[omry]

BaseContainer.{pretty,select,update_node} have all been deprecated in OmegaConf 2.0 and should no longer be used.

[titu1994]

Hi Omry - just a note. According to Semver - https://semver.org/#how-should-i-handle-deprecating-functionality, OmegaConf 2.1 should not have dropped this, but the next major version (say 3.0) should have dropped it.

While these are semantic rules (by definition) and are not enforced explicitly - it helps keep maintain compatibility with dependent downstream libraries.

[omry]

semver is a recommendation and not something all projects in the world follows.