Bump capistrano from 3.14.1 to 3.15.0 (#15537)

* Bump capistrano from 3.14.1 to 3.15.0

Bumps [capistrano](https://github.com/capistrano/capistrano) from 3.14.1 to 3.15.0.
- [Release notes](https://github.com/capistrano/capistrano/releases)
- [Commits](https://github.com/capistrano/capistrano/compare/v3.14.1...v3.15.0)

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

* Fix config/deploy.rb

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Yamagishi Kazutoshi <ykzts@desire.sh>

Gemfile.lock

@@ -116,7 +116,7 @@ GEM
       bundler (>= 1.2.0, < 3)
       thor (>= 0.18, < 2)
     byebug (11.1.3)
-    capistrano (3.14.1)
+    capistrano (3.15.0)
       airbrussh (>= 1.0.0)
       i18n
       rake (>= 10.0.0)
@@ -272,7 +272,7 @@ GEM
     httplog (1.4.3)
       rack (>= 1.0)
       rainbow (>= 2.0.0)
-    i18n (1.8.5)
+    i18n (1.8.7)
       concurrent-ruby (~> 1.0)
     i18n-tasks (0.9.33)
       activesupport (>= 4.0.2)
@@ -604,7 +604,7 @@ GEM
       actionpack (>= 4.0)
       activesupport (>= 4.0)
       sprockets (>= 3.0.0)
-    sshkit (1.21.0)
+    sshkit (1.21.1)
       net-scp (>= 1.1.2)
       net-ssh (>= 2.8.0)
     stackprof (0.2.16)
@@ -697,7 +697,7 @@ DEPENDENCIES
   browser
   bullet (~> 6.1)
   bundler-audit (~> 0.7)
-  capistrano (~> 3.14)
+  capistrano (~> 3.15)
   capistrano-rails (~> 1.6)
   capistrano-rbenv (~> 2.2)
   capistrano-yarn (~> 2.0)