Spf-validator

* Add Validation for too-many includes by superstes in https://github.com/fpcorso/spf-validator/pull/4
* Add Validation for unknown/invalid parts by superstes in https://github.com/fpcorso/spf-validator/pull/5
* Update dependency to allow for the newest version of dnspython (2.7.0)
* Fix for catchall matching by superstes in https://github.com/fpcorso/spf-validator/pull/6

* Update the required version of dnspython. There is a vulnerability in the dnspython<2.6.1 (see https://nvd.nist.gov/vuln/detail/CVE-2023-29483) so please upgrade as soon as you can. (Thanks seifert for the PR!)

* Fix SPF version regex to catch scenarios when there is not a space between the version and the next mechanism.

* Add a check for when the record is over the 255-character maximum
* Add a check for when the record is using the deprecated ptr mechanism
* Misc tweaks

* Adds checks for `ip4:` and `ip6:` mechanisms in SPF

* Initial Release