Record.values/value can be used interchangeably

- All of the `if data isn't a list turn it into one in the value type
  validates are no longer needed, they'll always be passed a list now`
- Special case to handle PTR/target values since it previously was
  single value and is now values

See README for more information

Add filters for checking record values

Create two new filters, ValueAllowlistFilter and ValueRejectlistFilter
that allow checing the value(s) of records to include or exclude,
similar to the name filters that alread exist

Add list_zones to AutoArpa

- This makes it possible to use dynamic zone config with AutoArpa
- Document what gotchas that entails
- Add tests both with another source (for generating zones to populate) and without (no zones to populate)

Add ASCII validation to ChunkedValue, TXT/SPF

Add support for checksum matching for safer plan & apply

Error message for zone not found in config.yaml

readme: add NixOS-DNS to mentioned projects

Fix bug in MetaProcessor up to date record check

Support for nested config env variable expansion

Version 1.4.0 bump & changelog update

Fix MetaProcessor.include_target

Add Processor.process_source_and_target_zones

ValuesMixin._data improvements & related fixes of Record.copy

Update README.md

Ignore deprecation warnings during tests