Upgrade rubocop and opt-in to all new cops

.rubocop.yml

@@ -55,3 +55,27 @@ Style/TrailingCommaInHashLiteral:
 # I actually use this a lot with `private :foo=`
 Style/AccessModifierDeclarations:
   Enabled: false
+
+#
+# Opt-ins for new cops from v0.81+ onwards
+#
+Layout/EmptyLinesAroundAttributeAccessor:
+  Enabled: true
+Layout/SpaceAroundMethodCallOperator:
+  Enabled: true
+Lint/DeprecatedOpenSSLConstant:
+  Enabled: true
+Lint/RaiseException:
+  Enabled: true
+Lint/StructNewOverride:
+  Enabled: true
+Style/ExponentialNotation:
+  Enabled: true
+Style/HashEachMethods:
+  Enabled: true
+Style/HashTransformKeys:
+  Enabled: true
+Style/HashTransformValues:
+  Enabled: true
+Style/SlicingWithRange:
+  Enabled: true

.simplecov

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 SimpleCov.start do
   minimum_coverage 100
 end

Gemfile.lock

@@ -32,7 +32,6 @@ GEM
       guard (~> 2.0)
       rubocop (~> 0.20)
     iniparse (1.5.0)
-    jaro_winkler (1.5.4)
     json-schema (2.8.1)
       addressable (>= 2.4)
     listen (3.1.5)
@@ -49,7 +48,7 @@ GEM
       childprocess (>= 0.6.3, < 4)
       iniparse (~> 1.4)
     parallel (1.19.1)
-    parser (2.7.0.3)
+    parser (2.7.1.3)
       ast (~> 2.4.0)
     pry (0.13.1)
       coderay (~> 1.1)
@@ -74,17 +73,19 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.9.0)
     rspec-support (3.9.2)
-    rubocop (0.80.1)
-      jaro_winkler (~> 1.5.1)
+    rubocop (0.84.0)
       parallel (~> 1.10)
       parser (>= 2.7.0.1)
       rainbow (>= 2.2.2, < 4.0)
       rexml
+      rubocop-ast (>= 0.0.3)
       ruby-progressbar (~> 1.7)
-      unicode-display_width (>= 1.4.0, < 1.7)
-    rubocop-performance (1.5.2)
+      unicode-display_width (>= 1.4.0, < 2.0)
+    rubocop-ast (0.0.3)
+      parser (>= 2.7.0.1)
+    rubocop-performance (1.6.0)
       rubocop (>= 0.71.0)
-    rubocop-rspec (1.38.1)
+    rubocop-rspec (1.39.0)
       rubocop (>= 0.68.1)
     ruby-progressbar (1.10.1)
     ruby_dep (1.5.0)
@@ -94,7 +95,7 @@ GEM
       simplecov-html (~> 0.11)
     simplecov-html (0.12.2)
     thor (0.20.3)
-    unicode-display_width (1.6.1)
+    unicode-display_width (1.7.0)
 
 PLATFORMS
   ruby