Bump the all group with 1 update (#483)

Updates the requirements on [rubocop-performance](https://github.com/rubocop/rubocop-performance) to permit the latest version.
- [Release notes](https://github.com/rubocop/rubocop-performance/releases)
- [Changelog](https://github.com/rubocop/rubocop-performance/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop-performance@v1.19.1...v1.20.0)

---
updated-dependencies:
- dependency-name: rubocop-performance
  dependency-type: direct:production
  dependency-group: all
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile

@@ -8,7 +8,7 @@ gem "faraday", "~> 2.7.11"
 gem "pry", "~> 0.14.2"
 gem "rspec", "~> 3.12.0"
 gem "rubocop", "~> 1.59.0"
-gem "rubocop-performance", "~> 1.19.1"
+gem "rubocop-performance", "~> 1.20.0"
 gem "rubocop-rake", "~> 0.6.0"
 gem "rubocop-rspec", "~> 2.25.0"
 gem "simplecov", "~> 0.22.0"

lib/feedjira/feed_entry_utilities.rb

@@ -63,11 +63,11 @@ def each
     end
 
     def [](field)
-      instance_variable_get("@#{field}")
+      instance_variable_get(:"@#{field}")
     end
 
     def []=(field, value)
-      instance_variable_set("@#{field}", value)
+      instance_variable_set(:"@#{field}", value)
     end
   end
 end

lib/feedjira/feed_utilities.rb

@@ -74,7 +74,7 @@ def update_attribute(feed, name)
       if old_value == new_value
         false
       else
-        send("#{name}=", new_value)
+        send(:"#{name}=", new_value)
         true
       end
     end