Update rspec-rails requirement from ~> 3.1 to ~> 6.0

[Tabby]

Recreation of the PR from dependabot due to CI changes. Also fixes errors and warnings from RSpec, either pre-existing or due to the dependency bump

Updates the requirements on rspec-rails to permit the latest version.

Changelog

Sourced from rspec-rails's changelog.

6.0.0

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Enhancements:

• Support Rails 7
• Template tweaks to remove instance variables from generated specs. (Takuma Ishikawa, #2599)
• Generators now respects default path configuration option. (@​vivekmiyani, #2508)

Breaking Changes:

• Drop support for Rails below 6.1
• Drop support for Ruby below 2.5 (following supported versions of Rails 6.1)
• Change the order of after_teardown from after to around in system specs to improve compatibility with extensions and Capybara. (Tim Diggins, #2596)

Deprecations:

• Deprecates integration spec generator (rspec:integration) which was an alias of request spec generator (rspec:request) (Luka Lüdicke, #2374)

5.1.2 / 2022-04-24

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Bug Fixes:

• Fix controller scaffold templates parameter name. (Taketo Takashima, #2591)
• Include generator specs in the inferred list of specs. (Jason Karns, #2597)

5.1.1 / 2022-03-07

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Bug Fixes:

• Properly handle global id serialised arguments in have_enqueued_mail. (Jon Rowe, #2578)

5.1.0 / 2022-01-26

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Enhancements:

• Make the API request scaffold template more consistent and compatible with Rails 6.1. (Naoto Hamada, #2484)
• Change the scaffold rails_helper.rb template to use require_relative. (Jon Dufresne, #2528)

5.0.3 / 2022-01-26

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... (truncated)

Commits

• 0646044 v6.0.0
• 7cd6f93 s/upload_backups_spec.rb/upload_backups_job_spec.rb/g
• 8016684 Merge pull request #2587 from rspec/shanecav84/include-tagged-logging
• 0b4d164 Fixed typo
• 396c68f This updates Rubocop and uses the .rubocop_rspec_base.yml for consistency
• efd4e6f Respect RSpec default_path for generators #2508
• 40192d2 Remove legacy
• 126da71 Remove version-specific checks for unsupported Rails/Ruby
• 49f7dd5 Add integration generator deprecation to changelog
• f604d5f Add only one test for integration generator deprecation
• Additional commits viewable in compare view