Bump rubocop-rspec from 3.1.0 to 3.4.0

Note we're renaming the RSpec/StringAsInstanceDoubleConstant rule to
RSpec/VerifiedDoubleReference because its name changed in version 3.4.0

Bumps [rubocop-rspec](https://github.com/rubocop/rubocop-rspec) from 3.1.0 to 3.4.0.
- [Release notes](https://github.com/rubocop/rubocop-rspec/releases)
- [Changelog](https://github.com/rubocop/rubocop-rspec/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rubocop/rubocop-rspec/compare/v3.1.0...v3.4.0)

---
updated-dependencies:
- dependency-name: rubocop-rspec
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile.lock

@@ -577,7 +577,7 @@ GEM
       rack (>= 1.1)
       rubocop (>= 1.52.0, < 2.0)
       rubocop-ast (>= 1.31.1, < 2.0)
-    rubocop-rspec (3.1.0)
+    rubocop-rspec (3.4.0)
       rubocop (~> 1.61)
     rubocop-rspec_rails (2.30.0)
       rubocop (~> 1.61)
@@ -791,7 +791,7 @@ DEPENDENCIES
   rubocop-factory_bot (~> 2.26.1)
   rubocop-performance (~> 1.23.1)
   rubocop-rails (~> 2.29.1)
-  rubocop-rspec (~> 3.1.0)
+  rubocop-rspec (~> 3.4.0)
   rubocop-rspec_rails (~> 2.30.0)
   rvm1-capistrano3 (~> 1.4.0)
   sassc-embedded (~> 1.80.1)