Bump letter_opener_web from 1.4.1 to 2.0.0 (#16960)

Bumps [letter_opener_web](https://github.com/fgrehm/letter_opener_web) from 1.4.1 to 2.0.0.
- [Release notes](https://github.com/fgrehm/letter_opener_web/releases)
- [Changelog](https://github.com/fgrehm/letter_opener_web/blob/master/CHANGELOG.md)
- [Commits](https://github.com/fgrehm/letter_opener_web/compare/v1.4.1...v2.0.0)

---
updated-dependencies:
- dependency-name: letter_opener_web
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

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

Gemfile

@@ -130,7 +130,7 @@ group :development do
   gem 'binding_of_caller', '~> 1.0'
   gem 'bullet', '~> 6.1'
   gem 'letter_opener', '~> 1.7'
-  gem 'letter_opener_web', '~> 1.4'
+  gem 'letter_opener_web', '~> 2.0'
   gem 'memory_profiler'
   gem 'rubocop', '~> 1.23', require: false
   gem 'rubocop-rails', '~> 2.12', require: false

Gemfile.lock

@@ -327,10 +327,11 @@ GEM
       addressable (~> 2.7)
     letter_opener (1.7.0)
       launchy (~> 2.2)
-    letter_opener_web (1.4.1)
+    letter_opener_web (2.0.0)
-      actionmailer (>= 3.2)
+      actionmailer (>= 5.2)
-      letter_opener (~> 1.0)
+      letter_opener (~> 1.7)
-      railties (>= 3.2)
+      railties (>= 5.2)
+      rexml
     link_header (0.0.8)
     llhttp-ffi (0.4.0)
       ffi-compiler (~> 1.0)
@@ -719,7 +720,7 @@ DEPENDENCIES
   kaminari (~> 1.2)
   kt-paperclip (~> 7.0)
   letter_opener (~> 1.7)
-  letter_opener_web (~> 1.4)
+  letter_opener_web (~> 2.0)
   link_header (~> 0.0)
   lograge (~> 0.11)
   makara (~> 0.5)