Update RuboCop toolchain for Ruby 3.4 support

Add racc gem required by RuboCop parser in Ruby 3.4+, and update RuboCop
to version 1.60+ which recognizes Ruby 3.4 as a supported version.

Key changes:
- Add racc gem (required by parser gem in Ruby 3.4+)
- Update rubocop from 1.28.2 to 1.81.7 (adds Ruby 3.4 support)
- Update rubocop-rspec from 2.10.0 to 3.8.0
- Modernize .rubocop.yml configuration:
  - Change 'require' to 'plugins' (new preferred syntax)
  - Replace deprecated RSpec/FilePath with RSpec/SpecFilePathFormat and
    RSpec/SpecFilePathSuffix
  - Update RSpec/VerifiedDoubleReference config (obsolete EnforcedStyle)

This allows the buildpack's code quality tools to work with Ruby 3.4.7.

Author: ramonskie

.rubocop.yml

@@ -1,5 +1,5 @@
 ---
-require:
+plugins:
   - rubocop-rspec
 
 AllCops:
@@ -67,7 +67,7 @@ Lint/EmptyBlock:
 RSpec/MultipleMemoizedHelpers:
   Max: 10
 RSpec/VerifiedDoubleReference:
-  EnforcedStyle: string
+  Enabled: false
 Style/OptionalBooleanParameter:
   Enabled: false
 Lint/RedundantCopDisableDirective:

Gemfile

@@ -6,14 +6,15 @@ source 'https://rubygems.org'
 gem 'base64'
 gem 'bigdecimal'
 gem 'digest'
+gem 'racc'
 gem 'set'
 gem 'tmpdir'
 
 group :development do
   gem 'rake'
   gem 'redcarpet'
   gem 'rspec'
-  gem 'rubocop'
+  gem 'rubocop', '~> 1.60'
   gem 'rubocop-rspec'
   gem 'rubyzip'
   gem 'tee'

Gemfile.lock

@@ -3,7 +3,7 @@ GEM
   specs:
     addressable (2.8.0)
       public_suffix (>= 2.0.2, < 5.0)
-    ast (2.4.2)
+    ast (2.4.3)
     base64 (0.3.0)
     bigdecimal (3.3.1)
     crack (0.4.5)
@@ -12,15 +12,21 @@ GEM
     digest (3.2.1)
     fileutils (1.8.0)
     hashdiff (1.0.1)
-    parallel (1.22.1)
-    parser (3.1.2.0)
+    json (2.16.0)
+    language_server-protocol (3.17.0.5)
+    lint_roller (1.1.0)
+    parallel (1.27.0)
+    parser (3.3.10.0)
       ast (~> 2.4.1)
+      racc
+    prism (1.6.0)
     public_suffix (4.0.7)
+    racc (1.8.1)
     rainbow (3.1.1)
     rake (13.0.6)
     redcarpet (3.5.1)
-    regexp_parser (2.3.1)
-    rexml (3.2.5)
+    regexp_parser (2.11.3)
+    rexml (3.4.4)
     rspec (3.11.0)
       rspec-core (~> 3.11.0)
       rspec-expectations (~> 3.11.0)
@@ -34,28 +40,32 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.11.0)
     rspec-support (3.11.0)
-    rubocop (1.28.2)
+    rubocop (1.81.7)
+      json (~> 2.3)
+      language_server-protocol (~> 3.17.0.2)
+      lint_roller (~> 1.1.0)
       parallel (~> 1.10)
-      parser (>= 3.1.0.0)
+      parser (>= 3.3.0.2)
       rainbow (>= 2.2.2, < 4.0)
-      regexp_parser (>= 1.8, < 3.0)
-      rexml
-      rubocop-ast (>= 1.17.0, < 2.0)
+      regexp_parser (>= 2.9.3, < 3.0)
+      rubocop-ast (>= 1.47.1, < 2.0)
       ruby-progressbar (~> 1.7)
-      unicode-display_width (>= 1.4.0, < 3.0)
-    rubocop-ast (1.17.0)
-      parser (>= 3.1.1.0)
-    rubocop-rspec (2.10.0)
-      rubocop (~> 1.19)
-    ruby-progressbar (1.11.0)
+      unicode-display_width (>= 2.4.0, < 4.0)
+    rubocop-ast (1.48.0)
+      parser (>= 3.3.7.2)
+      prism (~> 1.4)
+    rubocop-rspec (3.8.0)
+      lint_roller (~> 1.1)
+      rubocop (~> 1.81)
+    ruby-progressbar (1.13.0)
     rubyzip (2.3.2)
     set (1.1.2)
     tee (1.0.0)
     terminal-table (3.0.2)
       unicode-display_width (>= 1.1.1, < 3)
     tmpdir (0.3.1)
       fileutils
-    unicode-display_width (2.1.0)
+    unicode-display_width (2.6.0)
     webmock (3.14.0)
       addressable (>= 2.8.0)
       crack (>= 0.3.2)
@@ -71,10 +81,11 @@ DEPENDENCIES
   base64
   bigdecimal
   digest
+  racc
   rake
   redcarpet
   rspec
-  rubocop
+  rubocop (~> 1.60)
   rubocop-rspec
   rubyzip
   set