Remove Rails 7 builds

`rspec-rails` 6.0 will support Rails 7

Author: pirj

.github/workflows/ci.yml

@@ -16,19 +16,6 @@ jobs:
       fail-fast: false
       matrix:
        include:
-         # Rails Master (7.0) builds >= 2.7
-         - ruby: 3.1
-           env:
-             RAILS_VERSION: '~> 7.0.0'
-         - ruby: '3.0'
-           allow_failure: true
-           env:
-             RAILS_VERSION: '~> 7.0.0'
-         - ruby: 2.7
-           allow_failure: true
-           env:
-             RAILS_VERSION: '~> 7.0.0'
-
          # Rails 6.1 builds >= 2.5
          - ruby: 3.1
            env: