Rails 7.0 Support

The primary change for this release is support for Rails 7.0, with one breaking change.

• Using #encrypted_attributes is no longer supported. Instead, use #attr_encrypted_encrypted_attributes to avoid collision with Active Record 7 native encryption.

Dropping support for Rails 3 and 4

Support for Rails 3 and 4 was dropped as part of this release.

What's Changed

• Change version to 3.1.0 in Readme by @f3ndot in https://github.com/attr-encrypted/attr_encrypted/pull/297
• Add frozen_string_literal: true by @dillonwelch in https://github.com/attr-encrypted/attr_encrypted/pull/302
• Fix random OpenSSL::Cipher::CipherErrors/iv argument errors by @bfreese in https://github.com/attr-encrypted/attr_encrypted/pull/320
• Use a lazy load hook to configure Active Record by @eugeneius in https://github.com/attr-encrypted/attr_encrypted/pull/327
• Fixed a typo in docs by @bitsapien in https://github.com/attr-encrypted/attr_encrypted/pull/328
• Only load key if needed by @ankane in https://github.com/attr-encrypted/attr_encrypted/pull/310
• Make note about unique key/IV pair more prominent in docs by @ankane in https://github.com/attr-encrypted/attr_encrypted/pull/333